Synthesis of a variety of bichromophoric "ball-and-chain" systems based on buckminsterfullerene (C60) for the study of intramolecular electron and energy transfer processes

5032

J . Org. Chem. 1996, 61, 5032-5054

Syn th esis of a Va r iety of Bich r om op h or ic “Ba ll-a n d -Ch a in ”

System s Ba sed on Bu ck m in ster fu ller en e (C₆₀) for th e Stu d y of

In tr a m olecu la r Electr on a n d En er gy Tr a n sfer P r ocesses

J ames M. Lawson,^†Anna M. Oliver,^†Daniel F. Rothenfluh,^†Yi-Zhong An,^‡George A. Ellis,^‡

Millagahamada G. Ranasinghe,^†Saeed I. Khan,^‡Andreas G. Franz,^‡Padma S. Ganapathi,^‡

Michael J . Shephard,^†Michael N. Paddon-Row,*^,†and Yves Rubin*^,‡

School of Chemistry, University of New South Wales, Sydney, NSW, 2052, Australia, and Department of

Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569

Received March 15, 1996^X

Diels-Alder reaction of C₆₀with the 1,3-dienes 7e-h , 8a , 8b, and 8d -h affords the “ball-and-

chain” systems 2e-h , 3a , 3b, and 3d -h bearing two chromophores linked via a rigid, hybrid

saturated polynorbornane-bicyclo[2.2.0]hexane (“norbornylogous”) hydrocarbon bridge. Analogous

reaction with the bis(diene) 9 affords the soluble dumbbell system 4 bearing two C₆₀chromophores.

The norbornylogous bridge is a strong mediator of electron and energy transfer via a through-

bond coupling mechanism. The norbornylogous donor-bridge-diene units 7d -h , 8a , 8b, and 8d -h

were prepared in a straightforward manner from bicyclo[2.2.2]octane precursors by extending the

bridges with linearly fused norbornane-bicyclo[2.2.0]hexane moieties through execution of the

tandem Mitsudo-Smith series of reactions. The X-ray structure of the dimethoxybenzene-bridge-

C

₆₀system 3a reveals favorable self-complementarity manifested by the unusual packing structure

of 3a in the crystal. Molecular mechanics, semiempirical, and ab initio conformational analyses of

compounds 2e, 3a , 3b, 3e, 3f, 3h , 68, and 70 (MM2, Sybyl, CVFF, AM1, HF/3-21G) were performed

to quantify their ability to adopt two nondegenerate boat conformations, i.e., extended and folded

conformers, as well as their kinetic barrier of interconversion. A similar treatment of the C₆₀-

bridge-C₆₀system 4 revealed unusual preference for the folded-folded conformer (18.9 kcal/mol

at CVFF level), which was not reproduced by the AM1 method (0.11 kcal/mol). The reduction

potentials of the systems 2e, 3a , and 3e were about 0.1-0.5 V more negative than C₆₀, and the

third reduction potential (E³) of the 6-bond system 2e was 0.14 V more negative than the

corresponding wave for the 10-bond system 3e. This shift was attributed to the closer proximity

of the dimethylaniline donor group to the C₆₀surface for 2e vs 3e.

In tr od u ction

Furthermore, the unusual photophysical and redox

properties of C₆₀have made it the focus of many studies

of energy and electron transfer between this framework

and other chromophores.^7,8An important issue to be

resolved in such studies is how the dynamics of energy

and electron transfer depend on the distance and relative

orientation between the C₆₀group and the electron-

donating chromophore. This problem is best handled

using rigid covalently linked donor-bridge-acceptor

systems in which the two chromophores can be held at

well-defined distances and orientations with respect to

each other by a rigid bridge, which is generally either a

The functionalization of buckminsterfullerene (C₆₀) is

a burgeoning area of research, and a number of recent

studies have demonstrated the ease by which this

fascinating molecule undergoes a wide range of addition

reactions with unsaturated systems.^1,2We have exploited

the Diels-Alder reaction between C₆₀and 1,3-dienes to

obtain a variety of highly stable adducts which have

properties similar to those of C₆₀.^2-4A major reason for

the intense interest in functionalized fullerenes lies in

the exceptional electronic structure of the C₆₀cage,

reflected by its rich redox chemistry, its magnetic and

electronic properties, and its photophysical behavior.^1a

In particular, the characteristic electronic properties of

fullerenes suggest that suitably functionalized deriva-

tives may have important applications in fields as diverse

as conductive materials⁵and biological chemistry.^3d,6

(5) (a) Haddon, R. Acc. Chem. Res. 1992, 25, 127-133. (b) Holczer,

K.; Whetten, R. L. Carbon 1992, 30, 1261-1276.

(6) (a) Friedman, S. H.; Decamp, D. L.; Sijbesma, R. P.; Srdanov,

G.; Wudl, F.; Kenyon, G. L. J . Am. Chem. Soc. 1993, 115, 6506-6509.

(b) Shinazi, R. F.; Sijbesma, R. P.; Srdanov, G.; Hill, C. L.; Wudl, F.

Antimicrob. Agents Chemother. 1993, 37, 1707-1710. (c) Tokuyama,

H.; Yamago, S.; Nakamura, E.; Shiraki, T.; Sugiura, Y. J . Am. Chem.

Soc. 1993, 115, 7918-7919. (d) Boutorine, A. S.; Tokuyama, H.;

Takasugi, M.; Isobe, H.; Nakamura, E.; He´le`ne, C. Angew. Chem., Int.

Ed. Engl. 1994, 33, 2462-2465. (e) Toniolo, C.; Bianco, A.; Maggini,

M.; Scorrano, G.; Prato, M.; Marastoni, M.; Tomatis, R.; Spisani, S.;

Palu´, G.; Balir, E. D. J . Med. Chem. 1994, 37, 4558-4562. (f) Yamago,

S.; Tokuyama, H.; Nakamura, E.; Kikuchi, K.; Kananishi, S.; Sueki,

K.; Nakahara, H.; Enomoto, S.; Ambe, F. Chem. Biol. 1995, 2, 385-

389. (g) An, Y.-Z.; Chen, C.-h. B.; Anderson, J . L.; Sigman, D. S.; Foote,

C. S.; Rubin, Y. Tetrahedron 1996, 52, 5179-5189.

^†University of New South Wales.

^‡University of California, Los Angeles.

^XAbstract published in Advance ACS Abstracts, J uly 1, 1996.

(1) (a) Hirsch, A. The Chemistry of the Fullerenes; Thieme Verlag:

Stuttgart, 1994. (b) Diederich, F.; Thilgen, C. Science 1996, 271, 317-

323. (c) Taylor, R.; Walton, D. R. M. Nature 1993, 363, 685-693.

(2) An, Y.-Z.; Ellis, G. A.; Viado, A. L.; Rubin, Y. J . Org. Chem. 1995,

60, 6353-6361; see references cited therein.

(7) (a) Sension, R. J .; Szarka, A. Z.; Smith, G. R.; Hochstrasser, R.

Chem. Phys. Lett. 1991, 185, 179-183. (b) Wang, Y. J . Phys. Chem.

1992, 96, 764-767. (c) Arbogast, J . W.; Foote, C. S.; Kao, M. J . Am.

Chem. Soc. 1992, 114, 2277-2279. (d) Williams, R. M.; Verhoeven. J .

W. Chem. Phys. Lett. 1992, 194, 446-451. (e) Osaki, T.; Tai, Y.;

Tazawa, M.; Tanemura, S.; Inukai, K.; Ishiguro, K.; Sawaki, Y.; Saito,

Y.; Shinohara, H.; Nagashima, H. Chem. Lett. 1993, 789-792. (f)

Caspar, J . V.; Wang, Y. Chem. Phys. Lett. 1994, 218, 221-228. (g)

Foote, C. S. Top. Curr. Chem. 1994, 169, 347-363.

(3) (a) Rubin, Y.; Khan, S. I.; Freedberg, D. I.; Yeretzian, C. J . Am.

Chem. Soc. 1993, 115, 344-345. (b) Khan, S. I.; Oliver, A. M.; Paddon-

Row, M. N.; Rubin, Y. J . Am. Chem. Soc. 1993, 115, 4919-4920. (c)

An, Y. Z.; Anderson, J . L.; Rubin, Y. J . Org. Chem. 1993, 58, 4799-

4801. (d) Ganapathi, P. S.; Friedman, S. H.; Kenyon, G. L.; Rubin, Y.

J . Org. Chem. 1995, 60, 2954-2955.

(4) Anderson, J . L.; An, Y. Z.; Rubin, Y.; Foote, C. S. J . Am. Chem.

Soc. 1994, 116, 9763-9764.

“Ball and Chain” Systems Based on C₆₀

J . Org. Chem., Vol. 61, No. 15, 1996 5033

saturated hydrocarbon or a protein.⁹To date, there are

only a few reported studies of intramolecular electron

transfer in rigid covalently linked dyads in which one of

the chromophores is the C₆₀cage.^10,11

We have been studying intramolecular energy and

electron transfer processes in rigid, covalently linked,

multichromophoric systems such as 1(m ,n ) in which the

bridge is a polynorbornane-bicyclo[2.2.0]hexane hybrid

(“norbornylogous”) saturated hydrocarbon oligomer.^12-14

These studies have revealed that the norbornylogous

bridge strongly mediates both electron and energy trans-

fer over distances exceeding 12 Å by a through-bond

coupling mechanism.¹⁴

The ease with which we are able to alter systematically

both the length and configuration of our norbornylogous

bridge, together with the efficacy with which this type

of bridge mediates long-range intramolecular electron

and energy transfer, makes it an ideal unit for studying

the distance and orientation dependence of energy trans-

fer and electron transfer dynamics involving the C₆₀

system.

reactions with C₆₀, rather than the 2,3-bis(methylene)-

bicyclo[2.2.1]heptane group, on account of the compara-

tive ease with which bridges containing the former group

can be constructed. This methodology led ultimately to

the synthesis of the donor-bridge-dienes 7d -h , 8a , 8b,

and 8d -h and the tetraene 9 (Chart 2).

The key part of the synthesis is depicted in Scheme 1

and involves Diels-Alder reaction of 1,2,3,4-tetrachloro-

5,5-dimethoxycyclopentadiene to the terminal double

bond of the bridge to give the Diels-Alder adduct

possessing the stereochemistry depicted. Reductive

dechlorination of this material followed by deketalization

will lead to the formation of the 7-norbornenone system.

The 7-norbornenone group is known to be thermally

labile, readily losing carbon monoxide by a cheletropic

reaction to give the 1,3-cyclohexadiene system 5. Diels-

Alder reaction of 5 with dimethyl fumarate will form the

adduct 6, from which the bis(methylene) functionality

may be obtained via reduction of the ester groups,

bistosylation of the resulting bis(hydroxymethylene)

groups, and subsequent bisdehydrotosylation.

Synthesis of the extended bridges containing linearly

fused norbornane-bicyclo[2.2.0]hexane groups was

achieved through execution of the tandem Mitsudo¹⁶-

Smith¹⁷series of reactions as illustrated in Scheme 2.

This methodology has been well described in previous

papers.^13c,18,19Specific details of the bridge syntheses are

We report herein full details of our successful strategy

for synthesizing a variety of bichromophoric “ball-and-

chain” systems^3b2e-h , 3a , 3b, and 3d -h shown in Chart

1, in which the C₆₀group is tethered to several different

chromophores by our norbornylogous bridge of varying

length, ranging from the 6-bond systems 2e,g,h , to the

7-bond molecule 2f, to the 10-bond bichromophores 3a ,

3b, and 3d -g.¹⁵

(11) Williams, R. M.; Koeberg, M.; Lawson, J . M.; An, Y.-Z.; Rubin,

Y.; Paddon-Row, M. N.; Verhoeven, J . W. J . Org. Chem. 1996, 61, 5055.

(12) (a) Oevering, H.; Verhoeven, J . W.; Paddon-Row, M. N.;

Cotsaris, E.; Hush, N. S. Chem. Phys. Lett. 1988, 143, 488-495. (b)

Oevering, H.; Verhoeven, J . W.; Paddon-Row, M. N.; Cotsaris, E.; Hush,

N. S. Chem. Phys. Lett. 1988, 150, 179-180. (c) Kroon, J .; Oliver, A.

M.; Paddon-Row, M. N.; Verhoeven, J . W. J . Am. Chem. Soc. 1990,

112, 4868-4873.

(13) (a) Hush, N. S.; Paddon-Row, M. N.; Cotsaris, E.; Oevering, H.;

Verhoeven, J . W.; Heppener, M. Chem. Phys. Lett. 1985, 117, 8-11.

(b) Penfield, K. W.; Miller, J . R.; Paddon-Row, M. N.; Cotsaris, E.;

Oliver, A. M.; Hush, N. S. J . Am. Chem. Soc. 1987, 109, 5061-5065.

(c) Oevering, H.; Paddon-Row, M. N.; Heppener, H.; Oliver, A. M.;

Cotsaris, E.; Verhoeven, J . W.; Hush. N. S. J . Am. Chem. Soc. 1987,

109, 3258-3269. (d) Oliver, A. M.; Craig, D. C.; Paddon-Row, M. N.;

Kroon, J .; Verhoeven, J . W. Chem. Phys. Lett. 1988, 150, 366-373. (e)

Lawson, J . M.; Craig, D. C.; Paddon-Row, M. N.; Kroon, J .; Verhoeven,

J . W. Chem. Phys. Lett. 1989, 164, 120-125. (f) Antolovich, M.; Keyte,

P. J .; Oliver, A. M.; Paddon-Row, M. N.; Kroon, J .; Verhoeven, J . W.;

J onker, S. A.; Warman, J . M. J . Phys. Chem. 1991, 95, 1933-1941.

(g) Kroon, J .; Verhoeven, J . W.; Paddon-Row, M. N.; Oliver, A. M.

Angew. Chem., Int. Ed. Engl. 1991, 30, 1358-1361. (h) Lawson, J . M.;

Paddon-Row, M. N.; Schuddeboom, W.; Warman, J . M.; Clayton, A.

H.; Ghiggino, K. P. J . Phys. Chem. 1993, 97, 13099-13106. (i) Warman,

J . M.; Smit, K. J .; J onker, S. A.; Verhoeven, J . W.; Oevering, H.; Kroon,

J .; Paddon-Row, M. N.; Oliver, A. M. Chem. Phys. 1993, 170, 359-

380.

(14) Paddon-Row, M. N. Acc. Chem. Res. 1994, 27, 18-25.

(15) An n-bond ball-and-chain system is one in which the two

chromophores are connected by a bridge which has n σ-bonds separat-

ing them.

(16) (a) Mitsudo, T.; Kokuryo, K.; Shinsugi, T.; Nakagawa, Y.;

Watanabe, Y. J . Org. Chem. 1979, 44, 4492-4496. (b) Mitsudo, T.;

Naruse, H.; Kondo, T.; Ozaki, Y.; Watanabe, Y. Angew. Chem., Int.

Ed. Engl. 1994, 33, 580-581.

Resu lts a n d Discu ssion

Syn th etic Str a tegy for Br id ge Con str u ction . It

was decided to use the 2,3-bis(methylene)bicyclo[2.2.2]-

octane unit as the diene component in the Diels-Alder

(8) (a) Allemand, P.-M.; Koch, A.; Wudl, F.; Rubin, Y.; Diederich,

F.; Alvarez, M. M.; Anz, S. J .; Whetten, R. L. J . Am. Chem. Soc. 1991,

113, 1050-1051. (b) Xie, Q.; Pe´rez-Cordero, E.; Echegoyen, L. J . Am.

Chem. Soc. 1992, 114, 3978-3980. (c) Khaled, M. M.; Carlin, R. T.;

Trulove, P. C.; Eaton, G. R.; Eaton, S. S. J . Am. Chem. Soc. 1994, 116,

3465-3474. (d) Arias, F.; Echegoyen, L.; Wilson, S. R.; Lu, Q.; Lu, Q.

Y. J . Am. Chem. Soc. 1995, 117, 1422-1427. (e) Boyd, P. D. W.;

Bhyrappa, P.; Paul, P.; Stinchcombe, J .; Bolskar, R. D.; Sun, Y. P.;

Reed, C. A. J . Am. Chem. Soc. 1995, 117, 2907-2914. (f) Trulove, P.

C.; Carlin, R. T.; Eaton, G. R.; Eaton, S. S. J . Am. Chem. Soc. 1995,

117, 6265-6272.

(9) (a) Wasielewski, M. R. In Photoinduced Electron Transfer; Fox,

M. A., Chanon, M., Eds.; Elsevier: Amsterdam, 1988; Part A, p 161.

(b) Gust, D., Moore, T. A., Eds. Covalently Linked Donor-Acceptor

Species for Mimicry of Photosynthetic Electron and Energy Transfer

(Tetrahedron Symposium-in-Print No. 39), Tetrahedron 1989, 45. (c)

Wasielewski, M. R. Chem. Rev. 1992, 92, 435-461.

(10) (a) Williams, R. M.; Zwier, J . M.; Verhoeven, J . W. J . Am. Chem.

Soc. 1995, 117, 4093-4099. (b) Liddell, P. A.; Sumida, J . P.; Macpher-

son, A. N.; Noss, L.; Seely, G. R.; Clark, K. N.; Moore, A. L.; Moore, T.

A.; Gust, D. Photochem. Photobiol. 1994, 60, 537-541. (c) Drovetskaya,

T.; Reed, C. A.; Boyd, P. Tetrahedron Lett. 1995, 36, 7971-7974. (d)

Imahori, H.; Hagiwara, K.; Akiyama, T.; Taniguchi, S.; Okada, T.;

Sakata, Y. Chem. Lett. 1995, 265-266. (e) Linssen, T. G.; Du¨rr, K.;

Hanack, M.; Hirsch, A. J . Chem. Soc., Chem. Commun. 1995, 103-

104. (f) Warrener, R. N.; Elsey, G. M.; Houghton, M. A. J . Chem. Soc.,

Chem. Commun. 1995, 1417-1418.

(17) Smith, C. D. J . Am. Chem. Soc. 1959, 81, 4273-4274.

(18) (a) Paddon-Row, M. N.; Cotsaris, E.; Patney, H. K. Tetrahedron

1986, 42, 1779-1788. (b) Patney, H. K.; Paddon-Row, M. N. Synthesis

1986, 326-328. (c) Paddon-Row, M. N.; Patney, H. K. Synthesis 1986,

328-330. (d) Craig, D. C.; Lawson, J . M.; Oliver, A. M.; Paddon-Row,

M. N. J . Chem. Soc., Perkin Trans. 1 1990, 3305-3315. (e) Oliver, A.

M.; Paddon-Row, M. N. J . Chem. Soc., Perkin Trans. 1 1990, 1145-

1150. (f) Antolovich, M.; Oliver, A. M.; Paddon-Row, M. N. J . Chem.

Soc., Perkin Trans. 2 1989, 783-789. (g) Golka, A.; Keyte, P. J .;

Paddon-Row, M. N. Tetrahedron 1992, 48, 7663-7678. (h) Craig, D.

C.; Oliver, A. M.; Paddon-Row, M. N. J . Chem. Soc., Perkin Trans. 1

1993, 197-203. (i) Black, A. J .; Wooster, T. T.; Geiger, W. E.; Paddon-

Row, M. N. J . Am. Chem. Soc. 1993, 115, 7924-7925. (j) Atkinson, E.

J .; Oliver, A. M.; Paddon-Row, M. N. Tetrahedron Lett. 1993, 34, 6147-

6150. (k) Lawson, J . M.; Paddon-Row, M. N. J . Chem. Soc., Chem.

Commun. 1993, 1641-1643.

5034 J . Org. Chem., Vol. 61, No. 15, 1996

Lawson et al.

Ch a r t 1

presented in Schemes 3-7, most of which involve fairly

standard procedures and so will not be discussed in great

depth.

nilides 7d and 8d were best prepared from the corre-

sponding bis(hydroxymethyl) systems 17c (Scheme 3)

and 30c (Scheme 4), respectively. Protective acetylation

of the hydroxy groups in 17c and 30c followed by

nitration (Cu(NO₃)₂, Ac₂O) gave the nitro diacetates 34

and 35, which were converted into the bis(hydroxy-

methyl)acetanilides 38 and 39 by catalytic hydrogenation

of the nitro group, followed by protective acetylation of

the formed NH₂functionality, and subsequent reduction

of the acetoxy groups with LiBH₄. Bistosylation, followed

by base-induced bisdehydrotosylation gave the acetanil-

ide-dienes 7d and 8d . Basic hydrolysis of the acetanil-

ide 7d gave the aniline 42 which was exhaustively

methylated (MeI, NaHCO₃) to yield the quaternary

ammonium iodide 43. Reductive demethylation of this

compound with LiAlH₄completed the synthesis of the

N,N-dimethylaniline 7e which was obtained in an overall

yield of 9% from 17c.

The bridge dienes 7f, 7h , 8a , 8b, and 8h were readily

synthesized from the respective accessible norbornene

derivatives 10a ,b,f,h which already contain the chro-

mophore (either 1,4-dimethoxybenzene, 1,4-dimethoxy-

naphthalene, or anthracene) in its final form. These

chromophores are able to withstand the chemical reac-

tions used in the construction of the dienes (Schemes 3

and 4). The naphthoquinone-diene 8f was obtained in

good yield by treatment of the 1,4-dimethoxynaphtha-

lene-diene 8b with cerium(IV) ammonium nitrate (CAN)

under standard conditions.²⁰

The N,N-dimethylaniline-dienes 7e and 8e, and their

respective acetanilide derivatives 7d and 8d , were ob-

tained in the manner depicted in Scheme 5. The aceta-

The disappointingly low yield for the synthesis of 7e

by way of the acetanilide 7d prompted us to devise an

alternative, shorter synthesis of the N,N-dimethyl-

aniline-diene 8e bearing a longer bridge. Instead of

(19) Warrener, R. N.; Pitt, I. G.; Butler, D. N. J . Chem. Soc., Chem.

Commun. 1983, 1340-1342.

(20) J acob, P.; Callery, P. S.; Shulgrin, A. T.; Castagnoli, N. J . Org.

Chem. 1976, 41, 3627-3629.

“Ball and Chain” Systems Based on C₆₀

J . Org. Chem., Vol. 61, No. 15, 1996 5035

Ch a r t 2

Sch em e 1

Sch em e 2

Access to the dipyridophenazine-dienes 7g and 8g was

achieved using reactions which are outlined in Scheme

6. Nitration (Cu(NO₃)₂, Ac₂O) of bis(acetoxymethyl)-

acetanilides 36 and 37 gave the respective o-nitroaceta-

nilide derivatives 49 and 50. Treatment of the acetani-

lides with hydrazine hydrate effected the smooth removal

of the acetyl groups to give 51 and 52. Reduction of 51

and 52 using hydrazine hydrate and Pd/C led to the

formation of the respective o-phenylenediamines 53 and

54. Condensation of 53 and 54 with 1,10-phenanthroline-

5,6-dione (55) gave the dipyridophenazinediols 56 and

57, and these materials were readily converted into the

corresponding dienes 7g and 8g through sequential

deployment of the bistosylation and bisdehydrotosylation

reactions.

procuring this compound via the acetanilide-diene 8d

which, in turn, was obtained from the bis(hydroxymethyl)

compound 30c in low yield, the diester 29c, whose

synthesis is outlined in Scheme 4, was directly nitrated

to give 44. Catalytic hydrogenation of this material gave

a good yield of the aniline 45. Reductive methylation of

45 (H₂CdO, NaBH₄, dilute H₂SO₄) led to the formation

of the N,N-dimethylaniline 46 (80% yield), which was

then converted into the diene 8e using standard reac-

tions. The overall yield of 8e from the diester 29c was

27.5% as opposed to the 8.5% yield for 7e prepared from

the corresponding diester 16c.

The symmetrical 10-bond tetraene 9 was synthesized

from the known¹⁹6-bond diene 60 (Scheme 7). Thus,

compound 60 was reacted with 1,2,3,4-tetrachloro-5,5-

dimethoxycyclopentadiene to give the bisadduct 61.

5036 J . Org. Chem., Vol. 61, No. 15, 1996

Lawson et al.

Sch em e 3

Sch em e 4

Reductive dechlorination of this compound (Na, i-PrOH)²¹

led to the formation of 62, which was deprotected

(HCO₂H) to give the thermally labile bis-7-norbornenone

compound 63. Thermolysis of 63 in the presence of

dimethyl fumarate in refluxing toluene led to the direct

formation of the bisadduct 64 in excellent yield (94%).

Conversion of 64 into the required tetraene 9 was effected

in a straightforward manner.

Diels-Ald er Cycloa d d ition s w ith C₆₀

. The first

“ball-and-chain” system to be synthesized in our labora-

tory was compound 3a which bears a 1,4-dimethoxyben-

zene donor group (Chart 1).^3bCompound 3a , as well as

“Ball and Chain” Systems Based on C₆₀

J . Org. Chem., Vol. 61, No. 15, 1996 5037

Sch em e 5

Sch em e 6

Sch em e 7

of singlet oxygen, which leads to ene reaction products.^2,22

This problem is particularly critical in solution, as found

for compounds 2g and 3g (see below).

all Diels-Alder adducts except 4, was prepared by

addition of 1-1.5 equiv of diene via syringe pump (2-6

h) to a toluene solution of C₆₀maintained under reflux

to minimize the formation of bis and higher adducts.

Purification by flash chromatography over silica gel was

performed very conveniently by following the elution of

the brown-colored band(s). Most products obtained were

remarkably stable in the solid state and could be handled

without special precautions. However, we recently be-

came aware of the remarkable reactivity of C₆₀-fused

cyclohexene derivatives toward self-sensitized formation

The entire series of “ball-and-chain” systems obtained

by cycloaddition of the corresponding bridge dienes to C₆₀

5038 J . Org. Chem., Vol. 61, No. 15, 1996

Lawson et al.

Ch a r t 3

is displayed in Chart 1. The model bridge compound 3h

lacks a donor group and was prepared for comparison

purposes. Besides the dimethoxybenzene ball-and-chain

system 3a , we prepared the analogous 1,4-dimethoxy-

naphthalene systems 3b and 2f, the latter having a

shorter bridge to C₆₀. The dimethylanilino systems 2e

and 3e should lend themselves better than 3a , 3b, and

2f to photoinduced electron transfer studies, because of

the lower oxidation potential of this type of donor.^7c,10a,11

The naphthoquinone system 3f was prepared to study

both the electron correlation properties of its dianion

diradical and also the dynamics of the intramolecular

charge-shift process in the monoanion radical.²³The

most exciting compounds in this series are, perhaps, the

two dipyridophenazines 2g and 3g. Their complexation

with bis(bipyridine)ruthenium(II) moieties should give

systems prone to undergo photoinduced electron transfer

from ruthenium(II) to the C₆₀moiety.²⁴The large

distance between the donor and acceptor moieties should

prevent fast electron back-transfer, which is one of the

main problems encountered in systems designed to effect

the photochemical decomposition of water.^11,25,26

However, both dipyridophenazines 2g and 3g are

relatively unstable in solution, unlike the other systems

in this series. We believe that this effect is related to

1

the O₂-generating properties of fullerenes as mentioned

earlier, resulting in the oxidation of the dipyridophena-

zines system either by endoperoxide or N-oxide forma-

tion.²²We are currently working on the preparation of

simpler 1,10-phenanthroline-substituted bridges, which

when complexed to a transition metal should be much

more robust systems.²⁴

CS₂, albeit sparingly in the latter. Attempts to grow

crystals of 4 suitable for X-ray diffraction have so far led

to plates too thin to be usable. We are actively pursuing

this aspect of our work since we expect the packing of

this dumbbell molecule to be as interesting as that of

compound 3a (see below).

It seemed interesting to prepare a bis-C₆₀adduct such

as 4, as there are only a few examples of derivatives with

multiple C₆₀moieties connected by a rigid spacer.²⁷In

addition, there was a challenge in preparing this type of

system because the low solubility of compounds bearing

more than one fullerene moiety poses serious technical

problems.²This fact was observed in recent work by

Paquette et al. who describe the preparation of an

insoluble dumbbell system tied by a flexible bridge

comprising linearly fused 1,4-cyclohexadiene moieties.^27c

When tetraene 9 became available, we immediately set

out to prepare compound 4 using the general conditions

described above (toluene solvent). However, only prod-

ucts arising from the coupling of Diels-Alder intermedi-

ates were obtained in the form of a black insoluble

polymer (69). This material was insoluble in solvents

such as 1,2-dichlorobenzene, CS₂, or 1-methylnaphtha-

lene, which are excellent solvents for fullerenes. Fortu-

nately, we found that this reaction proceeded surprisingly

well in 1,2-dichlorobenzene at 135 °C, leading to a

remarkably high yield of compound 4 (81% based on

recovered C₆₀) which is soluble in 1,2-dichlorobenzene and

It is perhaps surprising that the different conditions

used for the preparation of 4 should give such dramati-

cally different experimental results. In particular, the

aspect of polymer formation is important because it could

lead to misinterpretation of limited available experimen-

tal data (e.g., CPMAS ¹³C NMR or IR) due to insolubility.

Calculations (see next section) on the two possible

conformations available for the mono-addition product

68 show that the folded conformation is marginally

preferred (1.02-2.80 kcal/mol, Chart 3). Given the small

energy difference between the two conformations, it

seems likely that either conformation may play some role

in lowering the reactivity of the fullerene core of 68

(monoadduct) toward further attack by another diene

moiety, as compared to unsubstituted C₆₀, by sterically

shielding a number of the reactive sites on the fullerene

surface (see space-filling model for the folded conforma-

tion of 68, Chart 3). This would favor further intermo-

lecular reaction between 68 and C₆₀producing 4, and not

between 68 and another molecule of 68 to ultimately form

polymeric material 69 (i.e., k₁. k₂> k₃). In addition,

the reactivity of the fullerene double bonds (at the 6,6-

ring junctions) is in general lowered by a significant

amount after the first addition of a group on C₆₀, which

permits, for example, the obtention of high yields of

monoadducts (up to ∼100% yield of 3a , based on recov-

ered C₆₀). However, this fact does not explain the

different course of the reaction taken in the two experi-

mental conditions. It seems most likely that the key

factor in the successful experiment using 1,2-dichlo-

robenzene is higher temperature and perhaps better

solubility. If the polymerization reaction leading to

(21) Lap, B. V.; Paddon-Row, M. N. J . Org. Chem. 1979, 44, 4979-

4981.

(22) An, Y.-Z.; Viado, A. L.; Arce, M.-J .; Rubin, Y. J . Org. Chem.

1995, 60, 8330-8331.

(23) For ESR studies on intramolecular charge shift processes in

anion radicals, see, for example: Gerson, F.; Wellauer, T.; Oliver, A.

M.; Paddon-Row, M. N. Helv. Chim. Acta 1990, 73, 1586-1601.

(24) Maggini, M.; Dono, A.; Scorrano, G.; Prato, M. J . Chem. Soc.,

Chem. Commun. 1995, 845-846.

(25) Igarashi, M.; Fukuda, M.; Taki, M.; Tago, T.; Minowa, T.;

Okada, Y.; Nishimura, J . Fullerene Sci. Technol. 1995, 3, 37-43.

(26) Yonemoto, E. H.; Riley, R. L.; Kim, Y. I.; Atherton, S. J .;

Schmehl, R. H.; Mallouk, T. E. J . Am. Chem. Soc. 1992, 114, 8081-

8087 and references cited therein.

(27) (a) Belik, P.; Gu¨gel, A.; Spickermann, J .; Mu¨llen, K. Angew.

Chem., Int. Ed. Engl. 1993, 32, 78-80. (b) Isaacs, L.; Seiler, P.;

Diederich, F. Angew. Chem., Int. Ed. Engl. 1995, 34, 1466-1469. (c)

Paquette, L. A.; Graham, R. J . J . Org. Chem. 1995, 60, 2958-2959.

polymer 69 is reversible at >130 °C (k_-3* 0 and k_-2

<

“Ball and Chain” Systems Based on C₆₀

J . Org. Chem., Vol. 61, No. 15, 1996 5039

k_-3),²⁸the reaction equilibrium will lead to the formation

of 4 via 68. The reaction essentially stops when the

concentrations of both 9 or 68 become negligible. It is

also possible that the formation of 69 is simply avoided

in 1,2-dichlorobenzene by the faster trapping of 68 with

excess C₆₀due to the higher temperature used. Finally,

solubility may affect the outcome of the reaction by

keeping 68 and especially 4 in solution as they are

produced. Coprecipitation of 4 and 68 would induce solid

state polymerization leading to 69. Meanwhile, there are

competing radical or ionic polymerization processes owing

to the reactive nature of the diene units in either 9 or

68, which explains the large discrepancy between isolated

and C₆₀-based yields of 4 (27 vs 81%).

F igu r e 1. ORTEP representation of the X-ray structure of

adduct 3a .

nique.²⁹As it stands, this problem is likely to be a major

stumbling block on the road to large fullerene-based

structures, at least until a general solution for mass

spectroscopy can be found. It is fortunate that 4 is

1

soluble and could be characterized by H and ¹³C NMR

spectroscopy, as well as FT-IR.

X-r a y Cr ysta llogr a p h ic Ch a r a cter iza tion . Com-

pound 3a was characterized by X-ray crystallography

(Figure 1).^3b,30The addition of diene 8a to C₆₀occurs at

the reactive 6,6-ring junction of C₆₀, which is always the

case for this type of reaction.¹The bond between the sp³-

hybridized carbons of C₆₀is elongated to 1.62(2) Å as was

also observed for the Diels-Alder adduct 70.^3aThe

distance between the center of the 1,4-dimethoxybenzene

unit to the median of the C₆₀sp³-sp³bond is 12.34 Å

and the shortest distances (R) between the two C₆₀sp³

carbons and C2 or C3 of the donor unit are 11.79 and

11.85 Å, respectively, in good agreement with the calcu-

lated values (11.814 and 11.822 Å, Figure 4). The rigid

norbornylogous bridge has a regular curvature, which is

an important feature in the ability of 3a to form dimeric

pairs in the crystal (Figure 2).

One of the most unusual and beautiful crystal-packing

arrangements we have observed is displayed in Figure

2. There is perfect but coincidental self-complementarity

of compound 3a in the crystal. This effect is reflected

by the arrangement of 3a in the lattice into head-to-tail

pairs, which may originate from the combination of

crystal-packing forces and electrostatic or π-stacking

interactions between the donor units and the C₆₀moiety.

Inspection of the space-filling model generated from the

coordinates for pairs of 3a (Biosym, Insight II) reveals

close contacts that are essentially within van der Waals

distances (Figure 3). The average of the C-H contact

distances between the norbornylogous axial hydrogens

pointing inward and the corresponding carbons on C₆₀is

3.09 Å. The shortest H-H distance between axial

hydrogens of paired units is 2.59 Å. The coincidental self-

complementarity of compound 3a is also reflected in its

unusual ability to form well-developed platelets, a prop-

erty which we were unable so far to reproduce for the

other compounds prepared in this study.

Characterization of the C₆₀-bridge-donor systems was

1

generally performed with relative ease. The H and ¹³C

NMR spectra of compounds 2e-h , 3a , 3b, 3d -h , and 4

immediately confirmed their structure. In particular, all

the allylic CH₂groups in direct proximity to the C₆₀cage

1

appeared as characteristic AB quartets in the H NMR

spectra. Owing to the C_ssymmetry of these compounds,

a total of 32 lines in the ¹³C NMR spectra are expected

for the fullerene framework. These were not always

observed in totality since electronic differentiation from

the first bicyclo[2.2.2]octene moiety in the norbornylogous

bridges is not very large and some spectra appear to be

a compromise between C_sand pseudo-C_2vsymmetries.

Mass spectral characterization was the most challenging

part of this work. A general tendency for all C₆₀deriva-

tives, especially those studied here, is to give fragmenta-

tion where C₆₀is the only recognizable ion. FAB MS was

successful in many cases, and matrix-assisted laser

desorption ionization (MALDI) mass spectroscopy also led

to positive results for some compounds. So far, however,

dumbbell compound 4 has resisted all mass spectrometric

attempts, even using Wilson’s mild electrospray tech-

Con for m a tion a l An a lysis. The ball-and-chain mol-

ecules are not totally rigid since the cyclohexene ring that

connects the bridge to the fullerene cage is able to adopt

two nondegenerate boat conformations, namely, an ex-

(28) (a) Rotello, V. M.; Howard, J . B.; Yadav, T.; Conn, M. M.; Viani,

E.; Giovane, L. M.; Lafleur, A. L. Tetrahedron Lett. 1993, 34, 1561-

1562. (b) Giovane, L. M.; Barco, J . W.; Yadav, T.; Lafleur, A. L.; Marr,

J . A.; Howard, J . B.; Rotello, V. M. J . Phys. Chem. 1993, 97, 8560-

8561. (c) Guhr, K. I.; Greaves, M. D.; Rotello, V. M. J . Am. Chem. Soc.

1994, 116, 5997-5998. (d) Nie, B.; Hasan, K.; Greaves, M. D.; Rotello,

V. M. Tetrahedron Lett. 1995, 36, 3617-3618. (e) Schlueter, J . A.;

Seaman, J . M.; Taha, S.; Cohen, H.; Lykke, K. R.; Wang, H. H.;

Williams, J . M. J . Chem. Soc., Chem. Commun. 1993, 972-974. (f)

Tsuda, M.; Ishida, T.; Nogami, T.; Kurono, S.; Ohashi, M. J . Chem.

Soc., Chem. Commun. 1993, 1296-1298. (g) Komatsu, K.; Murata, Y.;

Sugita, N.; Takeuchi, K.; Wan, T. S. M. Tetrahedron Lett. 1993, 34,

8473-8476. (h) Gonzalez, R.; Knight, B. W.; Wudl, F.; Semones, M.

A.; Padwa, A. J . Org. Chem. 1994, 59, 7949-7951.

(29) (a) Wilson, S. R.; Lu, Q. Y. Tetrahedron Lett. 1993, 34, 8043-

8046. (b) Wilson, S. R.; Wu, Y. H. J . Chem. Soc., Chem. Commun. 1993,

784-786.

(30) Compound 3a (C₉₂H₃₈O₂‚1.5C₆H₅Cl; M_r) 1344.17) crystallized

in the monoclinic space group P21/n with cell dimensions of a ) 25.180-

(5) Å, b ) 10.136(2) Å, c ) 25.241(5) Å, â ) 112.35(1)°, V ) 5958(2) Å³,

and an occupation of Z ) 4 in the unit cell. Data were collected at 20

°C on a Rigaku AFC5R diffractometer using graphite-monochromated

Cu KR radiation, to a maximum 2θ ) 115°, giving 8615 unique

reflections; the structure was solved by direct methods (SHELX86),

yielding R ) 0.116, R_w) 0.136 for 2604 independent reflections with

F > 6σ(F).

5040 J . Org. Chem., Vol. 61, No. 15, 1996

Lawson et al.

F igu r e 2. Crystal packing structure of the “ball-and-chain” system 3a .

of the fullerene cage and the point of attachment of the

non-C₆₀chromophore to the bridge, is quite different in

the two conformations, amounting to a difference of about

2.9 Å for the 10-bond system 3e and 2.75 Å for the 6-bond

system 2e.

Consequently, the dynamics of electron transfer and

energy transfer between the chromophores could well be

different for the two conformers. It is therefore necessary

to determine both the relative energies of the two

conformations and the energy barrier separating them

and to ascertain how these quantities depend on bridge

length and the nature of the non-C₆₀chromophore. The

last point is important since one, for example, might

envisage weak intramolecular attractive interactions

existing between the strong dimethylaniline donor group

and the C₆₀acceptor group in 3e, which may slightly

stabilize the folded conformer over the extended one.

There are limited experimental data that bear on this

issue. The X-ray crystal structure of 3a (Figure 1) reveals

that, in the solid state, this compound adopts the

extended conformation. However this preference is most

likely due to the presence of favorable intermolecular

interactions operating within the crystal structure. Line

shape analysis (¹H NMR) of the CH₂-allylic absorptions

of 3a indicate that both isomers are present in solution

and that one isomer is ca. 0.65 kcal/mol higher in energy

than the other (at -110 °C).^3bThe barrier to intercon-

version of the conformers has been determined in the

related benzannulated system 70,^3ain which the two

conformations are energetically degenerate. The free

energy barrier for this system was found to be ca. 14.6

kcal/mol.^3aHowever, the benzannulation of the cyclo-

hexene ring in 70 is expected to raise significantly the

barrier to cyclohexene ring inversion.

F igu r e 3. Space-filling model of the dimeric units in the

crystal for system 3a .

We have carried out a preliminary theoretical study

of the C₆₀-benzene system 70, the dimethylaniline

6-bond system 2e, the unsubstituted 10-bond system 3h ,

and a series of 10-bond systems bearing a variety of

chromophores (3a , 3b, 3e, and 3f). The molecular

geometries were fully optimized at the AM1 level of

theory,^31,32and single-point energies were obtained at the

Hartree-Fock level with the 3-21G basis set (HF/3-21G/

/AM1).³³

F igu r e 4. Calculated conformations for the dimethylaniline-

C₆₀system 3e. Distances R are AM1-optimized geometries.

tended conformer and a folded conformer. These confor-

mations are shown in Figure 4 for the case of the 10-

bond dimethylaniline system 3e. As may be clearly seen

from this figure, the direct, spatial inter-chromophore

separation, R, the closest distance between the surface

A fully optimized transition structure (TS) for the

interconversion between the extended and folded con-

formers was located at the AM1 level for 3e. As it was

“Ball and Chain” Systems Based on C₆₀

J . Org. Chem., Vol. 61, No. 15, 1996 5041

Ta ble 1. HF /3-21G//AM1 En er gy Differ en ces, ∆E_C(k ca l/

m ol), betw een th e F old ed a n d Exten d ed Con for m er s a n d

th e Activa tion En er gies, ∆E^q(k ca l/m ol), of th e Tr a n sition

Str u ctu r es Sep a r a tin g th e Tw o Con for m er s for a Ser ies

of C₆₀Ad d u cts

a

compd

∆E_C

-3.50

-0.42

-0.03

0.10

∆E^{q b}

3h

3a

3b

3e

3f

2e

68

70

7.79 (11.30)

9.89 (10.31)

9.20 (9.24)

9.88 (9.78)

9.89 (9.91)

9.62 (10.04)

2.65 (3.67)

17.61^d

-0.02

-0.42

-1.02 (-2.80)^c

d

a

A positive value indicates that the extended conformer is

b

favored. The activation energy with respect to the folded con-

former is given in parentheses. ^cBiosym Insight II CVFF force

field.^35cThe folded conformer is degenerate with the extended

d

conformer.

not feasible to locate the conformational transition

structures for the other molecules, approximate transi-

tion structures were obtained by fixing the “flap angle”

(the angle between the two mean planes of the cyclohex-

ene ring) equal to that of the TS of 3e and optimizing all

other degrees of freedom. In the case of 70, where the

folded and extended conformers are identical, the TS was

located by fixing the flap angle at 180°.

It was found that the conformational energy difference,

∆E_C, between the extended and folded conformations is

small in these molecules, with a slight preference for the

folded conformation (Table 1). For the dimethoxybenzene

molecule 3a , the folded conformation is slightly favored

by 0.51 kcal/mol which is in reasonable agreement with

the experimental value for this system (0.65 kcal/mol),

although it is uncertain which of the folded or extended

conformations is preferred in the NMR. In the case of

the 6-bond dimethylaniline system 2e, the folded con-

formation is slightly favored by ca. 0.42 kcal/mol, whereas

the extended conformation is favored for the 10-bond

analog 3e, but by only ca. 0.1 kcal/mol. Both conforma-

tions are isoenergetic for the dimethoxynaphthalene and

naphthoquinone molecules 3b and 3f, respectively. In-

terestingly, the unsubstituted system 3h exhibits the

largest conformational preference, with a ∆E_Cvalue of

3.50 kcal/mol, favoring the folded conformer. Clearly, the

remote electron-donating chromophores in these systems

are attenuating the natural preference of the unsubsti-

tuted hydrocarbon bridge, as in 3h , to adopt the folded

conformation. We have no ready explanation why this

should be so. However, we point out that a proper

treatment of long-range electronic and electrostatic in-

teractions that might exist between the chromophores

in 3a , 3b, 3e, and 3f requires the use of large basis sets

containing diffuse functions, together with inclusion of

electron correlation effects (neither of which has been

considered here, for purely technical reasons). Conse-

quently, the observed trends in the HF/3-21G//AM1 ∆E_C

values for these molecules should be treated with caution.

The calculated conformational activation barrier, ∆E^q,

for 70 is 17.61 kcal/mol (Table 1) which is in reasonable

F igu r e 5. Three unique conformations for dumbbell system

4. Distances are MM2-optimized geometries.

accord with the experimental value of 14.6 kcal/mol.

Therefore, the HF/3-21G//AM1 theoretical model should

give meaningful barrier heights for the ball-and-chain

molecules. The calculated ∆E^qvalues for the other

systems are ca. 50% lower than that for 70, and this is

probably due to increased steric congestion between the

C₆₀moiety and the bridge attached to the cyclohexene

ring in the ground state conformations of these systems,

compared to 70. However, the smaller inversion barriers

calculated for the ball-and-chain molecules, compared to

70, may also be related to the observation that the degree

of ring planarity and the size of the inversion barriers

along the series 1,4-cyclohexadiene, 1,4-dihydronaphtha-

lene, and 9,10-dihydroanthracene show strong influence

of benzannulation.³⁴The ∆E^qvalues are not noticeably

affected by the bridge length (cf. 2e and 3e) or by the

nature of the non-C₆₀chromophore (cf. 3a , 3b, 3e, and

3f).

Finally, we examined the dumbbell system 4 because

it is an interesting system for conformational and dy-

namic reasons. This molecule has two C₆₀moieties

connected by a 14-bond norbornylogous saturated hydro-

carbon bridge and can flex at the “hinges” formed by the

cyclohexene rings in a process somewhat similar to a pair

of bolas used by the gauchos (Figure 5). There are three

possible nondegenerate conformations that the dumbbell

can adopt: extended-extended, extended-folded, and folded-

folded. As with the preceding systems, the molecular

geometries were fully optimized at the AM1 level of

theory with no symmetry constraints (Table 2). Molec-

ular geometries were also optimized using three different

force fields,³⁵namely MM2,^35bSybyl,^35band CVFF.^35c

(31) Dewar, M. J . S.; Zoebisch, E. G.; Healy, E. F.; Stewart, J . J . P.

J . Am. Chem. Soc. 1985, 107, 3902-3909.

(32) Spartan version 4.0, Wavefunction, Inc., 18401 Von Karman

Ave. 370, Irvine, CA 92715.

(33) Gaussian 92, Revision A: Frisch, M. J .; Trucks, G. W.; Head-

Gordon, M.; Gill, P. M. W.; Wong, M. W.; Foresman, J . B.; J ohnson, B.

G.; Schlegel, H. B.; Robb, M. A.; Replogle, E. S.; Gomperts, R.; Andres,

J . L.; Raghavachari, K.; Binkley, J . S.; Gonzalez, C.; Martin, R. L.;

Fox, D. J .; Defrees, D. J .; Baker, J .; Stewart, J . J . P.; Pople, J . A.,

Gaussian, Inc., Pittsburgh, PA, 1992.

(34) Rabideau, P. W.; Lipkowitz, K. B.; Nachbar, R. B. J . Am. Chem.

Soc. 1984, 106, 3119-3123.

(35) (a) Burkert, U.; Allinger, N. L. in Molecular Mechanics, ACS

Monograph 177; American Chemical Society: Washington, DC, 1982.

(b) As implemented in Spartan, ref 32. (c) Biosym Insight II molecular

modeling package.

5042 J . Org. Chem., Vol. 61, No. 15, 1996

Lawson et al.

Ta ble 2. En er gy Differ en ces, ∆E_C(k ca l/m ol), a n d Closest

Ta ble 3. Red u ction P oten tia ls (vs Ag/AgCl) of C₆₀a n d

Ad d u cts 2e, 3a , a n d 3e (25 °C, THF , F c/F c⁺in ter n a l

C

₆₀/C₆₀Sep a r a tion s for th e Con for m er s of Du m bbell

System 4

r efer en ce, sca n r a te 100 m V s^-1

)

E¹

E²

E³

distance (Å)

compd

conformer

∆E_C(MM2)^a∆E_C(Sybyl)^a∆E_C(CVFF)^b∆E_C(AM1)^c

C₆₀

3a

2e

-0.86

-1.04

-1.10

-1.08

-1.38

-1.62

-1.69

-1.72

-1.97

-2.26

-2.50

-2.36

extended-

extended

folded-

extended

folded-

+9.32

16.53

+7.30

11.34

+8.43

16.07

+7.96

10.66

+18.85

16.56

+14.66

8.83

+0.11

15.78

+0.05

11.22

3e

Electr och em istr y. Diels-Alder adducts 2e, 3a , and

3e were reduced at more negative potentials than C₆₀by

about 0.1-0.3 V, which is reflective of the general trend

seen in 1,2-dihydrofullerene derivatives (Table 3).^39,40

With one exception, the nature of the non-C₆₀chro-

mophore has little effect on the reduction potentials. The

exception involves the third reduction potential of the

6-bond and 10-bond dimethylaniline systems 2e and 3e;

the former is 0.14 V more negative. This result suggests

a proximity effect, namely, greater electron repulsion

between the electron-rich system of the more proximate

aniline ring in the 6-bond system 2e and the C₆₀trianion,

as has been observed for the 1,4-dialkoxybenzene system

0 (rel.)

2.99

0 (rel.)

2.83

0 (rel.)

3.38

0 (rel.)

4.74

folded

a

b

From Spartan 4.0. Biosym Insight II molecular modeling

program. ^cMopac 93.00, Stewart, J . J . P., Fujitsu Limited, Tokyo,

1993; the PRECISE keyword was used for all geometry optimiza-

tions.

At the AM1 level of theory, the energy differences

between the three conformations are small (0.05-0.11

kcal/mol), although there is a slight preference for the

folded-folded conformation. Since the AM1 method mar-

ginally favors the extended conformation over the folded

conformation in ball-and-chain diene 68 possessing a

single C₆₀moiety (by 0.01 kcal/mol), the predicted pre-

ferred folded-folded conformation for 4 is most likely due

to the presence of weak, attractive π-π or van der Waals

interactions.³⁶The AM1 method severely underestimates

these types of interactions, and this is consistent with

the fairly large calculated closest separation of 4.5 Å

between the two C₆₀groups in the folded-folded confor-

mation.

In contrast, all three force field models, which have

been parametrized to take into account long-range in-

teractions between unsaturated groups,^35apredict a much

stronger preference for the folded-folded conformation,

by 7.3-14.7 kcal/mol, relative to the extended-folded

conformation, and by 8.4-18.9 kcal/mol, relative to the

extended-extended conformation. These methods also

predict the folded conformation to be preferred over the

extended conformation in 68, but only by ca. 1 kcal/mol.

The closest separation between the two C₆₀spheres in

the folded-folded conformation of the force field optimized

geometries is only ca. 2.8-3.4 Å, which clearly reflects

the strength of the attractive interactions between the

two C₆₀cages predicted by the force field methods. Such

interactions are probably exaggerated by the force field

calculations,³⁷but it does seem likely that the folded-

folded conformation is the genuine minimum energy

conformation for 4. One should note that shortest

intermolecular contacts as small as 3.13 Å have been

observed between C₆₀molecules in the X-ray structures

of C₆₀itself and its derivatives.³⁸

71.⁴⁰The closest contacts between sp²

and sp²

(C₆₀

)

(donor)

carbons are 4.48 Å for 3e and 3.10 Å for 71 (MM2).

P r elim in a r y P h otop h ysica l Stu d ies. Verhoeven

and Williams have carried out a preliminary photophysi-

cal study of the 6-bond anthracene system 2h and the

10-bond dimethylaniline molecule 3e in order to ascertain

whether intramolecular energy transfer and electron

transfer (ET) processes take place in these types of

molecules.¹¹The results are very exciting. Singlet-

singlet intramolecular energy transfer does, indeed, take

place in the anthracene 6-bond system 2h with a rate

constant of ca. 5 × 10⁷s^-1

.

Flash photolysis of the 10-bond aniline ball-and-chain

molecule 3e (benzonitrile solvent) results in rapid and

efficient intramolecular ET from the dimethylaniline

(DMA) donor to the C₆₀acceptor, to form the charge-

separated state, C₆₀^--bridge-DMA⁺. The rate constant

for this process is ca. 5.5 × 10⁹s^-1. The photoinduced

ET rate for 3e is comparable to that observed for the 10-

bond dimethylnaphthalene-dicyanovinyl system 1(1,1).^13c

This is unexpected since the driving force for photoin-

duced ET in 1(1,1) is greater than that for 3e. Clearly,

the electronic coupling between the C₆₀group and the

hydrocarbon bridge must be very strong in order to

compensate for the smaller driving force in 3e. Intrigu-

ingly, the lifetime of the C₆₀^--bridge-DMA⁺charge-

separated state is 250 ns (benzonitrile solvent), which is

quite long for bichromophoric charge-separated states.⁴¹

Con clu sion . The ball-and-chain systems 2e-h , 3a ,

3b, and 3d -h bearing the C₆₀and donor-substituted aryl

chromophores linked via a rigid norbornylogous hydro-

carbon bridge have been prepared and characterized.

Various calculations on compounds 2e, 3a , 3b, 3e, 3f, 3h ,

68, and 70 using molecular mechanics, semiempirical,

and ab initio methods show that there is little preference

between the folded and extended conformations, while

the activation barriers between the two conformers have

relatively consistent values (7.79-9.89 kcal/mol).

In summary, we conclude from the HF/3-21G//AM1

calculations that the bridge length and the nature of the

non-C₆₀chromophore have little effect on the relative

conformational energetics of these ball-and-chain mol-

ecules. However, this conclusion is subject to confirma-

tion using a higher level of theory that includes electron

correlation effects.

(36) (a) Hunter, C. A.; Sanders, J . K. M. J . Am. Chem. Soc. 1990,

112, 5525-5534. (b) Kurita, Y.; Takayama, C.; Tanaka, S. J . Comput.

Chem. 1994, 15, 1013-1018.

Preliminary photophysical studies clearly demonstrate

that rapid long-range intramolecular electron transfer

(37) In MM2, the exaggeration is introduced by the r^-6dependent

expression in the attractive energy term which accounts for van der

Waals interactions.

(39) (a) Wudl, F. Acc. Chem. Res. 1992, 25, 157-161. (b) Suzuki,

T.; Maruyama, Y.; Akasaka, T.; Ando, W.; Kobayashi, K.; Nagase, S.

J . Am. Chem. Soc. 1994, 116, 1359-1363.

(38) (a) Liu, S.; Lu, Y. J .; Kappes, M. M.; Ibers, J . A. Science 1991,

254, 408-410. (b) Bu¨rgi, H.-B.; Blanc, E.; Schwarzenbach, D.; Liu, S.;

Lu, Y.; Kappes, M. M.; Ibers, J . A. Angew. Chem., Int. Ed. Engl. 1992,

31, 640-643. (c) Fedurco, M.; Olmstead, M. M.; Fawcett, W. R. Inorg.

Chem. 1995, 34, 390-392. (d) Anderson, H. L.; Boudon, C.; Diederich,

F.; Gisselbrecht, J . P.; Gross, M.; Seiler, P. Angew. Chem., Int. Ed.

Engl. 1994, 33, 1628-1632.

(40) Illescas, B.; Mart´ın, N.; Seoane, C.; Delacruz, P.; Langa, F.;

Wudl, F. Tetrahedron Lett. 1995, 36, 8307-8310.

(41) Paddon-Row, M. N.; Oliver, A. M.; Warman, J . M.; Smit, K. J .;

de Haas, M. P.; Oevering, H.; Verhoeven, J . W. J . Phys. Chem. 1988,

92, 6958-6962.

“Ball and Chain” Systems Based on C₆₀

J . Org. Chem., Vol. 61, No. 15, 1996 5043

3.10 (s, 3H), 3.11 (m, 2H), 6.15 (m, 2H), 7.02 (dd, J ) 3.0, 5.5

Hz, 2H), 7.10 (dd, J ) 3.0, 5.5 Hz, 2H).

processes can take place in the ball-and-chain systems

and that the electronic coupling between the C₆₀chro-

mophore and the hydrocarbon bridge is unusually strong.

These molecules therefore offer considerable scope for

probing systematically the effect of distance, driving

force, and bridge configuration on the dynamics of

intramolecular energy and electron transfer processes in

C₆₀-based multichromophoric systems.¹⁴

(1r,4r,4a r,9â,9a r,10â)-1,4,4a ,9,9a ,10-Hexa h yd r o-1,4:9,

10-d im eth a n oa n th r a cen -12-on e (13c). 12c (22.5 g, 83.1

mmol) was dissolved in THF (200 mL) and formic acid (100

mL) and stirred for 18 h at 25 °C. The resulting solution was

poured onto water (100 mL) and extracted with CH₂Cl₂(2 ×

100 mL). The organic layers were combined, washed with

water (2 × 200 mL), saturated NaHCO₃(2 × 200 mL), brine

(200 mL), and dried over anhydrous Na₂SO₄. The solvent was

evaporated under reduced pressure to give an off-white oil

which was crystallized from methanol to give 13c as a white

solid (16.2 g, 87%), whose spectral properties are identical to

those previously reported:^{44 1}H NMR (300 MHz, CDCl₃) δ

(ppm) 1.27 (dt, J ) 1.2, 9.8 Hz, 1H), 2.28 (m, 2H), 2.71 (dt, J

) 1.8, 9.8 Hz, 1H), 3.18 (m, 2H), 3.37 (t, J ) 1.6 Hz, 2H), 6.48

(t, J ) 2.5 Hz, 2H), 7.08 (dd, J ) 3.0, 5.5 Hz, 2H), 7.12 (dd, J

) 3.0, 5.5 Hz, 2H).

Exp er im en ta l Section

Gen er a l. All reactions were performed under argon and,

for ¹O₂-sensitive compounds, in absence of light. The matrix

used for FAB mass spectra was m-nitrobenzyl alcohol. Matrix-

assisted laser desorption mass spectra (matrix: 9-nitroan-

thracene or 3,5-dihydroxybenzoic acid) were recorded in the

negative ion mode with relatively low laser power on a

PerSeptive Biosystems Voyager RP instrument (MALDI-TOF-

MS) or in the negative or positive ion modes by the group of

Charles L. Wilkins⁴²at the University of California, Riverside,

on a Waters-Extrel FTMS-2000 instrument (MALDI-FTMS).

Elemental microanalyses for 3a were carried out by Desert

Analytics, Tucson, AZ; microanalyses for all other compounds

were performed by Dr. H. P. Pham of the School of Chemistry,

UNSW. Column chromatography was performed on silica gel

70-230 mesh or 230-400 mesh (flash) from E. Merck or

Scientific Absorbents; thin layer chromatography (TLC) was

performed on glass plates coated with silica gel 60 F₂₅₄from

E. Merck.

Ma ter ia ls. The C₆₀/C₇₀soluble extract was obtained from

Texas Fullerene Corporation, Houston, TX, or from MER

Corporation, Tucson, AZ. Pure C₆₀was isolated using the

convenient procedure described by Tour et al.⁴³Reagents and

solvents were purchased reagent grade and used as received.

Anhydrous MgSO₄or Na₂SO₄was used as the drying agent

after workup in all the experiments. Solvent and other

impurities in the C₆₀derivatives were removed as described

earlier.²

Dim eth yl (1r,4r,4a â,9r,9a â,10r)-1,2,3,4,4a ,9,9a ,10-Oc-

t a h yd r o-1,4-et h en o-9,10-m et h a n oa n t h r a cen e-2,3-tr a n s-

d ica r boxyla te (15c). A mixture of 13c (20.6 g, 92.4 mmol)

and dimethyl fumarate (13.6 g, 94.7 mmol) in toluene (10 mL)

was heated at reflux for 14 h. The solvent was evaporated

under reduced pressure to give a brown oil which was

crystallized from methanol (100 mL) to give 15c as a white

powder (30.0 g, 96%): mp 124 °C; ¹H NMR (300 MHz, CDCl₃)

δ (ppm) 1.21 (d, J ) 9.5 Hz, 1H), 1.68 (dd, J ) 2.5, 8.3 Hz,

1H), 1.88 (dd, J ) 2.7, 8.3 Hz, 1H), 2.73 (dt, J ) 1.7, 9.5 Hz,

1H), 2.83 (dd, J ) 2.8, 5.8 Hz, 1H), 3.07 (dd, J ) 2.2, 5.8 Hz,

1H), 3.08 (br s, 1H), 3.10 (br s, 1H), 3.26 (m, 2H), 3.65 (s, 3H),

3.66 (s, 3H), 6.19 (t, J ) 7.2 Hz, 1H), 6.39 (dd, J ) 7.2 Hz,

1H), 7.00 (m, 2H), 7.08 (m, 2H); IR ν_max(Nujol) 3030, 3005,

1725, 1455, 1215, 1200, 1185, 1270, 1030, 740 cm^-1

. Anal.

Calcd for C₂₁H₂₂O₄: C, 74.53; H, 6.55. Found: C, 74.31; H,

6.78.

Dim eth yl (1r,4r,4a â,9r,9a â,10r)-1,2,3,4,4a ,9,9a ,10-Octa -

h yd r o-1,4-eth a n o-9,10-m eth a n oa n th r a cen e-2,3-tr a n s-d i-

ca r boxyla t e (16c). Compound 15c (29.5 g, 86.7 mmol) in

ethyl acetate (600 mL) was hydrogenated at 1 atm and 25 °C

using 10% Pd/C (0.30 g) until uptake of H₂had ceased. The

catalyst was removed by suction filtration, and the solvent was

evaporated under reduced pressure to give a clear oil. The

product was crystallized with methanol to give 16c as a white

Electr och em istr y. Cyclic voltammetry measurements

were performed on a BAS 100 electrochemical analyzer.

Experiments were conducted at 25 °C in a one-compartment

cell containing a glassy carbon working electrode, a platinum

wire auxiliary electrode, and a Ag/AgCl quasi-reference elec-

trode. As internal reference redox system the Fc/Fc⁺couple

was used with a redox potential measured to 0.45 V (vs Ag/

AgCl). Measurements were made on solutions of each sample

in THF (distilled from potassium/benzophenone) containing

1

solid (28.4 g, 96%): mp 110 °C; H NMR (300 MHz, CDCl₃) δ

(ppm) 1.31-1.52 (m, 3H), 1.54-1.66 (m, 3H), 1.75-1.86 (m,

1H), 2.18 (br d, J ) 10.0 Hz, 1H), 2.35 (br s, 1H), 2.40 (br s,

1H), 3.02 (br d, J ) 6.4 Hz, 1H), 3.15-3.20 (m, 3H), 3.62 (s,

3H), 3.71 (s, 3H), 7.02 (m, 2H), 7.12 (m, 2H); ¹³C NMR (75

MHz, CDCl₃) δ (ppm) 17.53, 22.23, 31.59, 32.01, 38.59, 43.72,

44.78, 46.44, 46.58, 46.78, 47.10, 52.10, 120.19, 120.38, 125.25,

150.22, 174.56, 174.90; IR ν_max(Nujol) 3030, 1725, 1490, 1210,

-

Bu₄N⁺BF₄(0.1 M, Aldrich) as supporting electrolyte with a

scan rate of 100 mV s^-1

.

Syn th esis. (1r,4r,4ar,9â,9ar,10â)-1,4,4a,9,9a,10-Hexah y-

dr o-1,4:9,10-dim eth an o-12,12-dim eth oxyan th r acen e (12c).

Sodium metal (127.0 g, 5.61 mol) was added piecewise to a

stirred, refluxing solution of 11c⁴⁴(48.3 g, 0.120 mol) in

2-propanol (800 mL) and THF (400 mL) over 5 h. After the

addition was completed, the resulting mixture was refluxed

for a further 12 h and then cooled to 25 °C. The reaction was

quenched by the addition of methanol (20 mL) and then water

(50 mL). The solvent was evaporated under reduced pressure

to give an off-white precipitate in an aqueous solution. Water

(500 mL) was added, and the resulting mixture was extracted

with CH₂Cl₂(3 × 200 mL). The organic layers were combined,

washed successively with water (500 mL), saturated NaHCO₃

(2 × 500 mL), and brine (500 mL), and dried over anhydrous

Na₂SO₄. The solvent was evaporated under reduced pressure

to give clear oil which was crystallized from methanol to give

12c as a white solid (29.1 g, 91%), whose spectral properties

are identical to those previously reported:^{44 1}H NMR (300 MHz,

CDCl₃) δ (ppm) 1.22 (d, J ) 9.7 Hz, 1H), 2.29 (t, J ) 1.8 Hz,

2H), 2.89 (dt, J ) 1.8, 9.7 Hz, 1H), 2.97 (m, 2H), 3.08 (s, 3H),

1195, 1180, 1030, 740 cm^-1

. Anal. Calcd for C₂₁H₂₄O₄: C,

74.09; H, 7.11. Found: C, 74.06; H, 7.08.

(1r,4r,4a â,9r,9a â,10r)-1,2,3,4,4a ,9,9a ,10-Octa h yd r o-1,4-

et h a n o-2,3-tr a n s-b is(h yd r oxym et h yl)-9,10-m et h a n oa n -

th r a cen e (17c). LiAlH₄(3.0 g, 79 mmol) was added portion-

wise to an ice cold, stirred solution of 16c (10.0 g, 29.4 mmol)

in dry THF (200 mL). After the addition was complete, the

reaction mixture was heated at reflux for 2 h. The reaction

mixture was cooled to 0 °C, and the excess reagent was

quenched by the sequential addition of water (12 mL), 15%

NaOH (12 mL), and then water (36 mL). The mixture was

filtered and the solvent evaporated under reduced pressure

to give a white solid which was recrystallized from CH₂Cl₂to

give 17c as a white powder (8.02 g, 96%): mp 163-164 °C; ¹H

NMR (300 MHz, CDCl₃) δ (ppm) 1.30-1.70 (m, 8H), 1.77-

1.86 (m, 3H), 2.27 (d, J ) 10.1 Hz, 1H), 2.31 (br s, 2H) 3.13 (s,

1H), 3.18 (s, 1H), 3.40 (t, J ) 9.4 Hz, 1H), 3.55 (dd, J ) 5.3,

9.4 Hz, 1H), 3.62 (d, J ) 4.1 Hz, 1H), 3.65 (d, J ) 1.5 Hz, 1H),

7.03 (dd, J ) 3.1, 5.4 Hz, 2H), 7.14 (dd, 3.1, J ) 5.4 Hz, 2H);

IR ν_max(Nujol) 3250 cm^-1. Anal. Calcd for C₁₉H₂₄O₂: C, 80.24;

H, 8.51. Found: C, 80.18; H, 8.46.

(42) Yao, J .; Castoro, J . A.; Wilkins, C. L., unpublished material.

(43) (a) Scrivens, W. A.; Bedworth, P. V.; Tour, J . M. J . Am. Chem.

Soc. 1992, 114, 7917-7919. (b) Scrivens, W. A.; Tour, J . M. J . Org.

Chem. 1992, 57, 6932-6936.

(44) McCulloch, R. K.; Rye, A. R.;Wege, D. Aust. J . Chem. 1974, 27,

1929-1941.

(1r,4r,4a â,5r,5a â,11bâ,12r,12a â)-1,2,3,4,4a ,5,5a ,11b,12,-

12a-Decah ydr o-1,4-eth an o-5,12-m eth an o-6,11-dim eth oxy-

2,3-bis(m eth ylen e)d iben zo[b,h ]bip h en ylen e (7f). A solu-

tion of 10f (14.0 g, 51 mmol)^18eand 1,2,3,4-tetrachloro-5,5-

dimethoxycyclopentadiene (14.5 g, 55 mmol) in xylene (bp

5044 J . Org. Chem., Vol. 61, No. 15, 1996

Lawson et al.

138-141 °C) (50 mL) was refluxed for 18 h. Azeotropic

removal of the xylene, through addition of ethanol (75 mL),

gave a solid residue which was assumed to be 11f (25.0 g, 89%)

since its 300 MHz ¹H NMR spectrum revealed the complete

absence of the peak at 6.25 ppm due to the double-bond protons

of 10f.

mixture was then stirred at 25 °C for 18 h. Ice water was

added, and the product was extracted with CH₂Cl₂(2 × 100

mL). The combined organic extracts were washed with water

(2 × 100 mL) and brine (3 × 50 mL) to remove all traces of

DMSO and dried, and the solvent was removed under reduced

pressure. The residue was then chromatographed (silica,

EtOAc:hexane 30:70) to give the pure diene 7f (0.75 g, 71%):

mp 182-183 °C (from EtOAc/pentane); ¹H NMR (300 MHz,

CDCl₃δ 1.48-1.52 (m, 2H), 1.72 (br s, 2H), 1.78-1.83

(overlapping multiplets, J ) 2 Hz, 4H), 2.37 (br s, 2H), 2.46

(br s, 2H), 3.46 (s, 2H), 4.10 (s, 6H), 4.77 (s, 2H), 5.31 (d, J )

1.2 Hz, 2H), 7.39 (m, 2H), 8.10 (m, 2H); ¹³C NMR (75 MHz,

CDCl₃) δ (ppm) 22.15, 28.22, 40.72, 43.19, 45.02, 51.55, 57.62,

103.04, 121.85, 122.51, 124.62, 126.82, 142.27, 150.44. Anal.

Calcd for C₂₇H₂₈O₂: C, 84.34; H, 7.34. Found: C, 84.08; H,

7.07.

Sodium metal (17.0 g, 0.74 mol) was added piecewise to a

refluxing solution of 11f (10.0 g, 18 mmol) in THF (200 mL)

and 2-propanol (400 mL), and the resulting mixture was

refluxed for a further 17 h. Methanol (50 mL) was added to

the cooled reaction mixture followed by crushed ice (200 g).

Extraction with CH₂Cl₂(3 × 150 mL) and evaporation of the

organic extracts (after washing with water and drying) gave

1

a solid whose H NMR spectrum revealed the presence of 12f,

together with compounds resulting from partial reduction of

the naphthalene ring. Rearomatization was achieved by

treating this material with DDQ (8.3 g, 34 mmol) in benzene

(100 mL) at 25 °C for 18 h. The reaction mixture was filtered,

and the filtrate was washed with 1 M NaOH (100 mL).

Evaporation of the dried filtrate gave a brownish solid which

was subjected to column chromatography (silica, EtOAc:

hexane 30:70). Although the eluted solid (5.6 g, 76%) was not

further purified, its identity as 12f was proven by ¹H NMR

(300 MHz, CDCl₃): δ (ppm) 0.86 (d, J ) 11.2 Hz, 1H), 2.14 (d,

J ) 11.4 Hz, 1H), 2.22 (s, 2H), 2.28 (s, 2H), 2.98 (m, 2H), 3.12

(s, 3H), 3.24 (s, 3H), 3.44 (s, 2H), 4.07 (s, 6H), 6.06 (t, J ) 2.3

Hz, 2H), 7.37 (m, 2H), 8.07 (m, 2H).

(1r,4r,4a â,5r,14r,14a â)-1,4,4a ,5,14,14a -Hexa h yd r o-1,4-

eth a n o-5,14-m eth a n o-2,3-bis(m eth ylen e)p en ta cen e (7h ).

A solution of 10h (1.0 g, 4.13 mmol)^18band 1,2,3,4-tetrachloro-

5,5-dimethoxycyclopentadiene (1.18 g, 4.45 mmol) in toluene

(20 mL) was refluxed for 18 h. The solvent was removed under

reduced pressure to give a solid residue which was assumed

1

to be 11h (2.0 g, 94%), since its 300 MHz H NMR spectrum

revealed the complete absence of the peak at 6.71 ppm due to

the double-bond protons of 10h .

Sodium metal (3.5 g, 0.15 mol) was added piecewise to a

refluxing solution of 11h (1.9 g, 3.85 mmol) in THF (50 mL)

and 2-propanol (200 mL). The resulting mixture was refluxed

for 17 h. Methanol (20 mL) was added to the cooled reaction

mixture followed by crushed ice (100 g). Extraction with CH₂-

Cl₂(3 × 100 mL) and evaporation of the organic extracts (after

washing with water and drying) gave a semisolid whose ¹H

NMR spectrum revealed the presence of 12h (1.15 g, 81%)

together with compounds resulting from partial reduction of

the naphthalene ring. Rearomatization was not performed on

this step.

A solution of the ketal 12f (5.6 g, 14 mmol) in formic acid

(100 mL) and THF (75 mL) was stirred for 18 h at 25 °C. The

formic acid was removed by extraction with water and

saturated NaHCO₃. Evaporation of the organic extracts gave

the ketone 13f as a fine white powder (4.5 g, 89%). This

material was unstable at elevated temperatures and could not

be fully characterized. 12f: IR ν_max(Nujol) 1770 cm^{-1 1}H

;

NMR (300 MHz, CDCl₃) δ (ppm) 0.97 (d, J ) 11.5 Hz, 1H),

1.98 (dt, J ) 1.7, 11.7 Hz, 1H), 2.27 (m, 2H), 2.51 (s, 2H), 3.18

(m, 2H), 3.46 (d, J ) 1.1 Hz, 2H), 4.07 (s, 6H), 6.42 (t, J ) 2.5

Hz, 2H), 7.38 (m, 2H), 8.09 (m, 2H).

A solution of the ketal 12h (1.15 g, 3.1 mmol) in formic acid

(50 mL) and THF (25 mL) was stirred for 18 h at 25 °C. The

formic acid was removed by extraction with water and

saturated NaHCO₃. Evaporation of the organic extracts gave

the ketone 13h (0.85 g, 84%). This material was unstable at

elevated temperatures and could not be fully characterized:

The synthesis of 15f from 13f was effected without isolation

of the intermediate diene 14f. Thus, a solution of the ketone

13f (4.25 g, 12 mmol) and dimethyl fumarate (1.8 g, 12.5 mmol)

in toluene (50 mL) was refluxed for 18 h. The solvent was

then removed under reduced pressure to give the diester 15f

(4.8 g, 85%) which was not purified further: ¹H NMR (300

MHz, CDCl₃) δ (ppm) 0.88 (d, J ) 11.2 Hz, 1H), 1.68 (d, J )

10.9 Hz, 1H), 1.87 (d, J ) 10.9 Hz, 1H), 2.06 (d, J ) 11.2 Hz,

1H), 2.24 (m, 2H), 2.84-3.43 (m, 6H), 3.66 (s, 3H), 3.79 (s, 3H),

4.04 (s, 6H), 6.12 (t, J ) 7.1 Hz, 1H), 6.30 (t, J ) 7.1 Hz, 1H),

7.37 (m, 2H), 8.07 (m, 2H).

Compound 15f (4.1 g, 8.7 mmol) in ethyl acetate (200 mL)

was hydrogenated at 1 atm and 25 °C using 10% Pd/C (200

mg) until uptake of H₂had ceased. Standard workup proce-

dures gave the saturated diester 16f as colorless needles (3.65

g, 91%): ¹H NMR (300 MHz, CDCl₃) δ (ppm) 1.25-1.78

(overlapping multiplets, 8H), 2.21-2.33 (m, 4H), 3.17 (m, 2H),

3.46 (m, 2H), 3.72 (s, 3H), 3.76 (s, 3H), 4.07(s, 6H), 7.37 (m,

2H), 8.08 (m, 2H).

To a suspension of LiAlH₄(0.48 g, 12.6 mmol) in anhydrous

THF (30 mL) was added a solution of 16f (3.0 g, 6.3 mmol) in

THF (100 mL), and the mixture was refluxed for 18 h. To the

chilled reaction mixture were added water (0.5 mL), 15%

NaOH (0.5 mL), and more water (1.5 mL) successively. The

mixture was then filtered, and the filtrate was dried over Na₂-

SO₄and evaporated under reduced pressure to give the diol

17f (2.5 g, 95%) which was not further purified.

IR ν_max(Nujol) 1770 cm^-1

.

The synthesis of 15h from 13h was effected without isola-

tion of the intermediate diene 14h . Thus, a solution of the

ketone 13h (0.8 g, 2.5 mmol) and dimethyl fumarate (0.4 g,

2.8 mmol) in toluene (20 mL) was refluxed for 18 h. The

solvent was then removed under reduced pressure to give the

diester 15h (0.9 g, 83%) which was not purified further.

Compound 15h (0.9 g, 2.05 mmol) in ethyl acetate (50 mL)

was hydrogenated at 1 atm and 25 °C using 10% Pd/C (50 mg)

until uptake of H₂had ceased. Standard workup procedures

gave the saturated diester 16h (0.8 g, 89%) whose ¹H NMR

spectrum revealed the absence of two peaks (triplets) at 6.17

and 6.38 ppm due to the double-bond protons and complete

reduction of the anthracene ring in the 9,10 positions. Rearo-

matization was achieved by treating this material with DDQ

(0.08 g, 0.35 mmol) in dry benzene (20 mL) at 25 °C for 5 h.

The reaction mixture was filtered, and the filtrate was washed

with a 1 M solution of NaOH (50 mL). Evaporation of the

dried filtrate gave a solid which was subjected to column

chromatography (silica, EtOAc:hexane 30:70) to obtain a brown

solid (0.50 g) which was not further purified. Its identity as

1

16h was proven by H NMR (300 MHz, CDCl₃): δ (ppm) 1.45

(d, J ) 9.9 Hz, 1H), 1.47-1.61 (overlapping multiplets, 4H),

1.66 (d, J ) 9.9 Hz, 1H), 1.70 (d, J ) 10.3 Hz, 1H), 2.40 (d, J

) 10.1 Hz, 1H), 2.44 (dt, J ) 2.3, 9.6 Hz, 2H), 3.17 (d, J )

10.4 Hz, 1H), 3.34 (d, J ) 9.7 Hz, 1H), 3.52 (d, J ) 9.7 Hz,

2H), 3.61 (s, 3H), 3.73 (s, 3H), 7.42 (m, 2H,), 7.59 (d, J ) 3.2

Hz, 2H), 7.94 (m, 2H), 8.28 (d, J ) 2.9 Hz, 2H).

To a suspension of LiAlH₄(0.10 g, 2.6 mmol) in anhydrous

THF (20 mL) was added a solution of 16h (0.5 g, 1.25 mmol)

in THF (50 mL), and the mixture was refluxed for 18 h. To

the chilled reaction mixture were added water (0.1 mL), 15%

NaOH (0.1 mL), and more water (0.3 mL) successively. The

mixture was then filtered, and the filtrate was dried over Na₂-

To a cooled (-5 °C) solution of the diol 17f (2.1 g, 5.0 mmol)

in dry pyridine (50 mL) was added p-toluenesulfonyl chloride

(2.0 g, 10.5 mmol), and the resulting mixture was maintained

at -5 °C for 36 h. The reaction was then quenched with

crushed ice, and the solution was extracted with CH₂Cl₂(3 ×

100 mL). The combined organic extracts were washed suc-

cessively with 1 M HCl (3 × 100 mL) and saturated NaHCO₃

(100 mL), before being dried and concentrated under reduced

pressure to give the ditosylate 18f (3.1 g, 85%) which was not

purified.

To a solution of the ditosylate 18f (2.0 g, 2.7 mmol) in dry

DMSO (50 mL) was added t-BuOK (1.0 g, 9.0 mmol). The

“Ball and Chain” Systems Based on C₆₀

J . Org. Chem., Vol. 61, No. 15, 1996 5045

SO₄and evaporated under reduced pressure to give the diol

17h (0.35 g, 80%) which was not further purified.

(1r,4r,4a â,4b r,4câ,5r,5a â,9a â,10r,10a r,10b r,10cr)-

1,2,3,4,4a ,4b ,4c,5,5a ,9a ,10,10a ,10b ,10c-Tet r a d eca h yd r o-

1,4:5,8-d im eth a n o-4b,8b-d im eth ylben zo[3′,4′]cyclobu ta -

[1′,2′:3,4]cyclobu ta [1,2-b]n a p h th a len e (27h ). A solution of

23h (5.0 g, 20.8 mmol) and 1,2,3,4-tetrachloro-5,5-dimethoxy-

cyclopentadiene (5.8 g, 22.0 mmol) in toluene (20 mL) was

refluxed for 18 h. The solvent was removed under reduced

pressure to give a solid residue which was assumed to be 24h

(9.5 g, 91%) since its 300 MHz ¹H NMR spectrum revealed

the complete absence of the peak at 5.99 ppm due to the

double-bond protons of 23h .

To a cooled (-5 °C) solution of the diol 17h (0.35 g, 0.9 mmol)

in dry pyridine (20 mL) was added p-toluenesulfonyl chloride

(0.3 g, 1.55 mmol), and the resulting mixture was maintained

at -5 °C for 36 h. The reaction was then quenched with

crushed ice, and the solution was extracted with CH₂Cl₂(3 ×

50 mL). The combined organic extracts were washed succes-

sively with 1 M HCl (3 × 50 mL) and saturated NaHCO₃(50

mL) before being dried and concentrated under reduced

pressure to give the ditosylate 18h (0.45 g, 71%) which was

not purified.

To the solution of the ditosylate 18h (0.4 g, 0.6 mmol) in

dry DMSO (20 mL) was added t-BuOK (0.23 g, 2 mmol). The

mixture was then stirred at 25 °C for 18 h. Ice water was

added, and the product was extracted with CH₂Cl₂(2 × 50

mL). The combined organic extracts were washed with water

(2 × 50 mL) and brine (3 × 50 mL) to remove all traces of

DMSO and dried, and the solvent was removed under reduced

pressure to give the diene 7h (0.13 g, 61%): mp 245-246 °C

(from EtOAc/pentane); ¹H NMR (300 MHz, CDCl₃) δ (ppm)

1.53 (s, 2H), 1.73 (d, J ) 10.4 Hz, 1H), 1.85 (s, 2H), 1.95 (dq,

J ) 2.5, 10.2 Hz, 2H), 2.46 (d, J ) 10.3 Hz, 1H), 2.62 (br s,

2H), 3.40 (s, 2H), 4.74 (s, 2H), 5.22 (d, J ) 0.6 Hz, 2H), 7.40

(m, 2H), 7.63 (s, 2H), 7.94 (m, 2H), 8.27 (s, 2H); ¹³C NMR (75

MHz, CDCl₃) δ (ppm) 22.10, 40.90, 42.66, 43.90, 46.49, 103.23,

117.16, 124.70, 125.61, 127.92, 131.25, 131.42, 148.78, 150.17.

Anal. Calcd for C₂₇H₂₄: C, 93.06; H, 6.94. Found: C, 92.83;

H, 7.06.

Dim eth yl (1r,4r,4a â,4br,4câ,5r,8r,8a r,8bâ,8cr)-1,4,4a ,-

4b ,4c,5,6,7,8,8a ,8b ,8c-Dod eca h yd r o-1,4:5,8-d im et h a n o-

ben zo[3′,4′]cyclobu ta [1′,2′:3,4]cyclobu ta [1,2]ben zen e-4b,-

8b-d ica r boxyla te (20h ). A solution of 19h (20.0 g, 84.7

mmol)¹⁶in quadricyclane (8.30g, 90 mmol) was refluxed for

18 h. Acetone (25 mL) was added to the cooled solution, and

the resulting precipitate was collected and recrystallized from

acetone to give 20h (24.0 g, 86.6%): mp 137-138 °C (from

EtOAc/pentane); ¹H NMR (300 MHz, CDCl₃) δ (ppm) 1.05 (m,

J ) 1.5 Hz, 1H), 1.07 (m, J ) 1.07 Hz, 1H), 1.08 (d, J ) 2.5

Hz, 1H), 1.10 (d, J ) 2.5 Hz, 1H), 1.12 (m, J ) 1.6 Hz, 1H),

1.15 (m, J ) 1.5 Hz, 1H), 1.46 (m, J ) 3.0 Hz, 1H), 1.48 (m, J

) 3.0 Hz, 1H), 2.10 (m, J ) 1.8 Hz, 1H), 2.12 (s, 2H), 2.14 (m,

J ) 1.8 Hz, 1H), 2.31 (s, 2H), 2.79 (m, J ) 1.6 Hz, 2H), 3.79 (s,

6H), 6.04 (t, J ) 1.8 Hz, 2H). Anal. Calcd for C₂₀H₂₄O₄: C,

73.15; H, 7.37. Found: C, 72.95; H, 7.30.

Sodium metal (15.0 g, 0.65 mol) was added piecewise to a

refluxing solution of 24h (9.5 g, 18.4 mmol) in THF (50 mL)

and 2-propanol (150 mL). The resulting mixture was refluxed

for 17 h. Methanol (20 mL) was added to the cooled reaction

mixture followed by crushed ice (100 g). Extraction with CH₂-

Cl₂(3 × 100 mL) and evaporation of the organic extracts (after

1

washing with water and drying) gave a solid whose H NMR

spectrum revealed the presence of 25h (6.0 g, 87%).

A solution of the ketal 25h (6.0 g, 16.3 mmol) in formic acid

(50 mL) and THF (25 mL) was stirred for 18 h at 25 °C. The

formic acid was removed by extraction with water and

saturated NaHCO₃. Evaporation of the organic extracts gave

the ketone 26h (4.5 g, 86%). This material was unstable at

elevated temperatures and could not be fully characterized:

IR ν_max(Nujol) 1770 cm^-1

.

A solution of the ketone 26h (4.5 g, 14.2 mmol) in toluene

(50 mL) was refluxed for 1 h. The solvent was then removed

under reduced pressure to give 27h (3.5 g, 85%): mp 159-

1

160 °C (from EtOAc/pentane); H NMR (300 MHz, CDCl₃) δ

(ppm) 0.74 (s, 6H), 1.06 (d, J ) 2.4 Hz, 1H), 1.08 (d, J ) 2.4

Hz, 1H), 1.18 (dt, J ) 1.6, 10.2 Hz, 1H), 1.48 (overlapping

multiplets, 2H), 1.57 (dt, J ) 1.7, 10.1 Hz, 1H), 1.61 (dt, J )

1.5, 10.2 Hz, 1H), 1.64 (dt, J ) 10.2 Hz, 1H), 1.81 (dt, J ) 1.5,

10.2 Hz, 1H), 1.87 (m, J ) 2.1 Hz, 2H), 1.97 (br s, 2H), 2.04

(m, J ) 2.1 Hz, 2H), 2.16 (br s, 2H), 2.42 (m, J ) 2.1 Hz, 2H),

5.35 (overlapping multiplets, 2H), 5.56 (overlapping multiplets,

2H). Anal. Calcd for C₂₂H₂₈: C, 90.35; H, 9.65. Found: C,

90.01; H, 9.25.

(1r,4r,4aâ,4br,4câ,5r,5aâ,6r,9r,9aâ,10r,10ar,10br,10cr)-

1,2,3,4,4a,4b,4c,5,5a,6,9,9a,10,10a,10b,10c-Hexadecah ydr o-

6,9-e t h a n o-1,4:5,8-d im e t h a n o-4b ,8b -d im e t h yl-7,8-b is-

(m eth ylen e)ben zo[3′,4′]cyclobu ta [1′,2′:3,4]cyclobu ta [1,2-

b]n a p h th a len e (8h ). A solution of 27h (3.0 g, 10.3 mmol)

and dimethyl fumarate (1.57 g, 11.0 mmol) in benzene (20 mL)

was refluxed for 18 h. The solvent was then removed under

reduced pressure to give the diester 28h (3.6 g, 81%) which

was not purified further.

Compound 28h (3.6 g, 8.07 mmol) in ethyl acetate (50 mL)

was hydrogenated at 1 atm and 25 °C using 10% Pd/C (50 mg)

until uptake of H₂had ceased. Standard workup procedures

gave the saturated diester 29h (3.5 g, 97%) whose ¹H NMR

spectrum revealed the absence of two peaks (triplets) at 6.12

and 6.32 ppm due to the double-bond protons.

To a suspension of LiAlH₄(0.57 g, 15 mmol) in anhydrous

THF (20 mL) was added a solution of 29h (3.5 g, 7.8 mmol) in

THF (50 mL), and the mixture refluxed for 18 h. To the chilled

reaction mixture were added water (0.5 mL), 15% NaOH (0.5

mL), and more water (1.5 mL) successively. The mixture was

then filtered, and the filtrate was dried over Na₂SO₄and

evaporated under reduced pressure to give the diol 30h (2.6

g, 84%) which was not further purified.

To a cooled (-5 °C) solution of the diol 30h (2.6 g, 6.6 mmol)

in dry pyridine (20 mL) was added p-toluenesulfonyl chloride

(3.0 g, 15.5 mmol), and the resulting mixture was maintained

at -5 °C for 36 h. The reaction was then quenched with

crushed ice, and the solution was extracted with CH₂Cl₂(3 ×

50 mL). The combined organic extracts were washed succes-

sively with 1 M HCl (3 × 50 mL) and saturated NaHCO₃before

being dried and concentrated under reduced pressure to give

the ditosylate 31h (4.5 g, 83%) which was not purified.

To a solution of the ditosylate 31h (4.0g, 5.7 mmol) in dry

DMSO (20 mL) was added t-BuOK (2.3 g, 2 mmol). The

mixture was then stirred at 25 °C for 18 h. Ice water was

added, and the product was extracted with CH₂Cl₂(2 × 50

mL). The combined organic extracts were washed with water

(2 × 50 mL) and brine (3 × 50 mL) to remove all traces of

(1r,4r,4aâ,4br,4câ,5r,8r,8ar,8bâ,8cr)-1,4,4a,4b,4c,5,6,7,8,-

8a ,8b,8c-Dod eca h yd r o-1,4:5,8-d im eth a n o-4b,8b-d im eth -

ylb en zo[3′,4′]cyclob u t a [1′,2′:3,4]cyclob u t a [1,2]b en zen e

(23h ). To a solution of 20h (20.0 g, 61.9 mmol) in dry THF

(300 mL) was added LiAlH₄(4.5 g, 0.120 mol) in small portions.

The mixture was refluxed for 18 h. To the cooled reaction

mixture were added successively water (4.5 mL), 15% NaOH

(4.5 mL), and water (13.5 mL). The mixture was then filtered,

and the filtrate was dried and evaporated under reduced

pressure to give the diol 21h (15.2 g, 91%) which was not

purified further: IR ν_max(Nujol) 3250 cm^-1

.

To a cooled solution (-5 °C) of the diol 21h (15.0 g, 55.1

mmol) in dry pyridine (100 mL) was added slowly methane-

sulfonyl chloride (12.6 g, 0.110 mol). The resulting solution

was maintained at -5 °C for 72 h, after which it was poured

onto crushed ice and then extracted with CH₂Cl₂(3 × 150 mL).

The organic extract was washed successively with 1 M HCl

(750 mL) and saturated NaHCO₃, then dried, and evaporated

to give the dimesylate 22h (16.5 g, 76%) which was not

purified.

A magnetically stirred mixture of the dimesylate 22h (16.5

g, 41.66 mmol) and LiAlH₄(3.0 g, 80 mmol) in dry THF (300

mL) was refluxed for 48 h. Use of a workup procedure that

was identical to that described above for the synthesis of the

diol gave 23h (9.1 g, 91%): mp 101-102 °C (from EtOAc/

pentane); ¹H NMR (300 MHz, CDCl₃) δ (ppm) 0.76 (s, 6H), 1.07

(dm, J ) 9.3 Hz, 2H), 1.13 (dt, J ) 1.5, 8.6 Hz, 1H), 1.21 (dt,

J ) 1.8, 10.0 Hz, 1H), 1.31 (br d J ) 8.7 Hz, 1H), 1.48 (dm, J

) 9.3 Hz, 2H), 1.57 (dt, J ) 1.9, 10.1 Hz, 1H), 1.73 (s, 2H),

1.89 (s, 2H), 2.12 (m, J ) 2.3 Hz, 2H), 2.69 (m, J ) 2.1 Hz,

2H), 5.99 (t, J ) 1.9 Hz, 2H). Anal. Calcd for C₁₈H₂₄: C,

89.94; H, 10.06. Found: C, 89.84; H, 10.03.

5046 J . Org. Chem., Vol. 61, No. 15, 1996

Lawson et al.

DMSO and dried, and the solvent was removed under reduced

pressure to give the diene 8h (1.55 g, 74%): mp 168-170 °C

(from EtOAc/pentane); ¹H NMR (300 MHz, CDCl₃) δ (ppm)

0.75 (s, 6H), 1.09 (dq, J ) 2.3, 5.4 Hz, 2H), 1.16 (dt, J ) 1.3,

9.9 Hz, 1H), 1.46 (overlapping multiplets, 5H), 1.52 (s, 2H),

1.56 (partially hidden d, 1H), 1.82-1.90 (m, 3H), 1.94 (br s,

4H), 2.01 (s, 2H), 2.04 (m, 2H), 2.30 (br s, 2H), 4.69 (s, 2H),

5.23 (d, J ) 1.1 Hz, 2H); ¹³C NMR (75 MHz, CDCl₃) δ (ppm)

9.73, 22.32, 28.62, 31.13, 35.07, 36.12, 39.18, 40.76, 45.17,

[1′,2′:3,4]cyclobu ta [1,2-b]n a p h th a len e (25a ). A solution of

23a (5.0 g, 14.4 mmol) and 1,2,3,4-tetrachloro-5,5-dimethoxy-

cyclopentadiene (4.0 g, 15 mmol) in xylene (bp 138-141 °C)

(30 mL) was refluxed for 18 h. Azeotropic removal of the

xylene, through addition of ethanol (50 mL), gave a solid

residue which was assumed to be 24a (7.7 g, 87%) since its

300 MHz ¹H NMR spectrum revealed the complete absence of

the peak at 5.98 ppm due to the double-bond protons of 23a .

Sodium metal (14.0 g, 0.61 mol) was added piecewise to a

refluxing solution of 24a (7.7 g, 12.6 mmol) in THF (100 mL)

and 2-propanol (400 mL). The resulting mixture was refluxed

for 17 h. Methanol (20 mL) was added to the cooled reaction

mixture followed by crushed ice (100 g). Extraction with CH₂-

Cl₂(3 × 150 mL) and evaporation of the organic extracts (after

washing with water and drying) gave a solid (4.8 g, 80.5%)

whose ¹H NMR spectrum revealed the presence of 25a : ¹H

NMR (300 MHz, CDCl₃) δ (ppm) 0.79 (s, 6H), 1.00 (d, J ) 10.9

Hz, 1H), 1.49 (d, J ) 9.5 Hz, 1H), 1.67 (d, J ) 9.4 Hz, 1H),

1.86 (s, 2H), 1.93 (br s, 4H), 1.99 (s, 2H), 2.28 (d, J ) 11.0 Hz,

1H), 3.06 (s, 3H), 3.13 (s, 3H), 3.45 (s, 2H), 3.79 (s, 6H), 6.03

(t, J ) 2.3 Hz, 2H), 6.58 (s, 2H).

45.19, 52.70, 54.20, 102.45, 151.05. Anal. Calcd for C₂₆H₃₄

C, 90.11; H, 9.89. Found: C, 90.30; H, 9.64.

:

Dim eth yl (2ar,3â,8â,8ar)-2a,3,8,8a-Tetr ah ydr o-3,8-m eth -

a n o-4,7-d im et h oxycyclob u t a [b]n a p h t h a len e-1,2-d ica r -

boxyla te (19a ). A magnetically stirred solution of 10a (38.5

g, 0.19 mol),⁴⁵DMAD (27.5 g, 0.193 mol), and RuH₂CO(PPh₃)₃

(0.6 g, 0.5 mmol)¹⁶in benzene (200 mL) was refluxed under

an argon atmosphere for 18 h. Ethanol was added to the

cooled reaction mixture, and the precipitated material was

collected and recrystallized from ethanol to give the ester 19a

1

(56.1 g, 86%): mp 168-169 °C (from ethanol); H NMR (300

MHz, CDCl₃) δ (ppm) 1.73 (s, 2H), 2.76 (s, 2H), 3.50 (s, 2H),

3.79 (s, 6H), 3.83 (s, 6H), 6.62 (s, 2H). Anal. Calcd for

C₁₉H₂₀O₆: C, 66.27; H, 5.85. Found: C, 66.15; H, 6.03.

Dim et h yl (1r,4r,4a â,4b r,4câ,5r,10r,10a â,10b r,10câ)-

1,4,4a ,4b,4c,5,10,10a ,10b,10c-Deca h yd r o-1,4:5,10-d im eth -

an o-6,9-dim eth oxyben zo[3′,4′]cyclobu ta[1′,2′:3,4]cyclobu ta-

[1,2-b]n aph th alen e-4b,10b-dicar boxylate (20a). A solution

of 19a (56.0 g, 0.163 mol) in quadricyclane (20.0 g, 0.217 mol)

was refluxed under an argon atmosphere for 18 h. Acetone

(25 mL) was added to the cooled solution, and the resulting

precipitate was collected and recrystallized from acetone to

(1r,4r,4a â,5r,5a â,5b r,5câ,6r,11r,11a â,11b r,11câ,12r,-

12a â)-1,4,4a ,5,5a ,5b ,5c,6,11,11a ,11b ,11c,12,12a -Te t r a -

d e c a h y d r o -1,4-e t h a n o -5,12:6,11-d im e t h a n o -7,10-d i-

m et h oxy-5b ,11b -d im et h yl-2,3-b is(m et h ylen e)n a p h t h o-

[2′′,3′′:3′,4′]cyclob u t a [1′,2′:3,4]cyclob u t a [1,2-b]n a p h t h a -

len e (8a ). A solution of the ketal 25a (3.0 g, 6.33 mmol) in

formic acid (50 mL) and THF (20 mL) was stirred for 18 h at

25 °C. The formic acid was removed by extraction with water

(3 × 100 mL) and saturated NaHCO₃(100 mL). Evaporation

of the organic extracts gave the ketone 26a as a fine white

powder (2.5 g, 91%). This material was unstable at elevated

temperatures and could not be fully characterized: IR ν_max

1

give 20a (51.2 g, 71.7%): mp 176-179 °C (from acetone); H

NMR (300 MHz, CDCl₃) δ (ppm) 1.14 (d, J ) 10.3 Hz, 1H),

1.51 (d, J ) 10.2 Hz, 1H), 1.88 (d, J ) 9.7 Hz, 1H), 2.07 (s,

2H), 2.30 (s, 2H), 2.32 (d, J ) 9.5 Hz, 1H), 2.86 (s, 2H), 3.56

(s, 2H,), 3.77 (s, 6H), 3.79 (s, 6H), 6.04 (t, J ) 1.6 Hz, 2H),

6.60 (s, 2H). Anal. Calcd for C₂₆H₂₈O₆: C, 71.54; H, 6.46.

Found: C, 71.76; H, 6.72.

(Nujol) 1780 cm^-1

.

A solution of the ketone 26a (2.5 g, 5.84 mmol) and dimethyl

fumarate (0.90 g, 6 mmol) in toluene (20 mL) was refluxed for

18 h. The solvent was then removed under reduced pressure

to give the diester 28a (3.0 g, 95%) which was not purified

further.

Compound 28a (3.0 g, 5.5 mmol) in ethyl acetate (200 mL)

was hydrogenated at 1 atm and 25 °C using 10% Pd/C (200

mg) until uptake of H₂had ceased. Standard workup proce-

dures gave the saturated diester 29a as colorless needles (2.9

g, 98%): ¹H NMR (300 MHz, CDCl₃) δ (ppm) 0.85 (s, 3H), 0.86

(s, 3H), 1.19-1.89 (overlapping multiplets, 12H), 1.92 (s, 2H),

1.99 (d, J ) 11.6 Hz, 2H), 2.04 (br d, J ) 11.4 Hz, 2H), 2.10

(dt, J ) 2.2, 12.5 Hz, 2H), 3.08 (s, 2H), 3.65 (s, 3H), 3.68 (s,

3H), 3.77(s, 3H), 3.79 (s, 3H), 6.58 (s, 2H).

To a suspension of LiAlH₄(0.38 g, 10 mmol) in anhydrous

THF (20 mL) was added a solution of 29a (3.0 g, 5.5 mmol) in

THF (100 mL), and the mixture was refluxed for 18 h. To the

chilled reaction mixture were added water (0.4 mL), 15%

NaOH (0.4 mL), and more water (1.2 mL) successively. The

mixture was then filtered, and the filtrate was dried over Na₂-

SO₄and evaporated under reduced pressure to give the diol

30a (2.5 g, 93%) which was not further purified.

To a cooled (-5 °C) solution of the diol 30a (2.5 g, 5.10 mmol)

in dry pyridine (50 mL) was added p-toluenesulfonyl chloride

(2.0 g, 10.5 mmol), and the resulting mixture was maintained

at -5 °C for 36 h. The reaction was then quenched with

crushed ice, and the solution was extracted with CH₂Cl₂(3 ×

100 mL). The combined organic extracts were washed suc-

cessively with 1 M HCl (3 × 100 mL) and saturated NaHCO₃

before being dried and concentrated under reduced pressure

to give the ditosylate 31a (4.0 g, 97%) which was not purified.

To a solution of the ditosylate 31a (4.0 g, 5.0 mmol) in dry

DMSO (50 mL) was added t-BuOK (2.0 g, 18.4 mmol). The

mixture was then stirred at 25 °C for 18 h. Ice water was

added, and the product was extracted with CH₂Cl₂(2 × 100

mL). The combined organic extracts were washed with water

(2 × 100 mL) and brine (3 × 50 mL) to remove all traces of

DMSO and dried, and the solvent was removed under reduced

pressure. The residue was then chromatographed (silica,

EtOAc:hexane 30:70) to give pure diene 8a (1.4 g, 62%): mp

212-213 °C (from EtOAc/pentane); ¹H NMR (300 MHz, CDCl₃)

δ (ppm) 0.89 (s, 6H), 1.43 (d, J ) 9.0 Hz, 2H), 1.45 (br s, 2H),

1.52 (dt, J ) 1.5, 9.2 Hz, 2H), 1.72 (br d, J ) 9.2 Hz, 1H), 1.86

(1r,4r,4a â,4b r,4câ,5r,10r,10a â,10b r,10câ)-1,4,4a ,4b ,-

4c,5,10,10a ,10b ,10c-Deca h yd r o-1,4:5,10-d im et h a n o-6,9-

d im et h oxy-4b ,10b -d im et h ylb en zo[3′,4′]cyclob u t a [1′,2′:

3,4]cyclobu ta [1,2-b]n a p h th a len e (23a ). To a solution of

20a (51.2 g, 0.117 mol) in dry THF (300 mL) was added LiAlH₄

(9.2 g, 0.245 mol) in small portions. The mixture was refluxed

for 18 h. To the cooled reaction mixture were added succes-

sively water (9.2 mL), 15% NaOH (9.2 mL), and water (27.6

mL). The mixture was then filtered, and the filtrate was dried

and evaporated under reduced pressure to give the diol 21a

(42.3 g, 95%) which was not purified further: IR ν_max(Nujol)

3250 cm^-1

.

To a cooled solution (-5 °C) of the diol 21a (42.0 g, 110

mmol) in dry pyridine (200 mL) was added slowly methane-

sulfonyl chloride (27.0 g, 0.236 mol). The resulting solution

was kept at -5 °C for 72 h, after which it was poured onto

crushed ice and then extracted with CH₂Cl₂(3 × 150 mL). The

organic extract was washed successively with 1 M HCl (750

mL) and saturated NaHCO₃(100 mL), then dried, and

evaporated to give the dimesylate 22a (53.0 g, 95%) which was

not purified.

A magnetically stirred mixture of the dimesylate 22a (53.0

g, 0.105 mol) and LiAlH₄(8.0 g, 0.22 mol) in dry THF (350

mL) was refluxed for 48 h. Use of a workup procedure that

was identical to that described above for the synthesis of the

diol gave 23a (32.5 g, 89%): mp 210-211 °C (from EtOAc/

pentane); ¹H NMR (300 MHz, CDCl₃) δ (ppm) 0.90 (s, 6H), 1.17

(d, J ) 8.7 Hz, 1H), 1.38 (d, J ) 8.7 Hz, 1H), 1.57 (d, J ) 9.6

Hz, 1H), 1.67 (s, 2H), 1.77 (d, J ) 9.4 Hz, 1H), 1.91 (s, 2H),

2.74 (s, 2H), 3.52 (s, 2H), 3.79 (s, 6H), 5.98 (t, J ) 1.8 Hz, 2H),

6.60 (s, 2H). Anal. Calcd for C₂₄H₂₈O₂: C, 82.72; H, 8.10.

Found: C, 82.44; H, 8.29.

(1r,4r,4a r,5â,5a r,5b â,5cr,6â,11â,11a r,11b â,11cr,12â,-

12a r)-1,4,4a ,5,5a ,5b ,5c,6,11,11a ,11b ,11c,12,12a -Te t r a -

d e ca h yd r o-1,4:5,12:6,11-t r im e t h a n o-7,10,15,15-t e t r a -

m eth oxy-5b,11b-d im eth yln a p h th o[2′′,3′′:3′,4′]cyclobu ta -

(45) Filipescu, N.; Chang, D. S. C. J . Am. Chem. Soc. 1972, 94,

5990-5996.

“Ball and Chain” Systems Based on C₆₀

J . Org. Chem., Vol. 61, No. 15, 1996 5047

(br d, J ) 9.3 Hz, 2H), 1.88 (s, 2H), 1.94 (s, 2H), 1.98 (d, J )

organic phases were dried and filtered, and the solvent was

removed under reduced pressure. The residue was chromato-

graphed (silica, EtOAc:hexane 20:80) to give pure 8b (2.68 g,

85%): mp decomposed above 250 °C (from hot hexane); ¹H

NMR (300 MHz, CDCl₃) δ (ppm) 0.96 (s, 6H), 1.44 (d, J ) 8.7

Hz, 2H), 1.48 (br s, 2H), 1.50 (d, J ) 10.4 Hz, 1H), 1.66 (d, J

) 9.5 Hz, 1H), 1.86 (d, J ) 8.2 Hz, 2H), 1.91 (d, J ) 10.4 Hz,

2H), 1.98 (d, J ) 11.3 Hz, 1H), 2.11 (s, 2H), 2.16 (s, 2H), 2.32

(br s, 2H), 3.65 (s, 2H), 3.98 (s, 6H), 4.68 (s, 2H), 5.22 (s, 2H),

7.41-7.46 (m, 2H), 8.05-8.10 (m, 2H); ¹³C NMR (75 MHz,

CDCl₃) δ (ppm) 9.79, 22.26, 31.14, 39.26, 40.50, 40.64, 42.79,

44.27, 44.98, 50.68, 53.93, 61.86, 102.62, 121.96, 124.94,

127.77, 135.31, 144.17, 150.77. Anal. Calcd for C₃₆H₄₀O₂: C,

85.67; H, 7.99. Found: C, 85.86; H, 8.15.

9.2 Hz, 1H), 2.07 (br s, 2H), 2.31 (br s, 2H), 3.47 (s, 2H), 3.79

(s, 6H), 4.69 (s, 2H), 5.23 (d, J ) 1.1 Hz, 2H), 6.60 (s, 2H); ¹³

C

NMR (75 MHz, CDCl₃) δ (ppm) 9.60, 22.31, 31.12, 39.31, 40.24,

40.70, 43.60, 43.69, 45.04, 49.74, 53.82, 56.10, 102.55, 109.00,

136.79, 147.80, 150.93. Anal. Calcd for C₃₂H₃₈O₂: C, 84.54;

H, 8.42. Found: C, 84.03; H, 8.67.

Dim eth yl (1r,4r,4a â,5r,5a â,5br,5câ,6r,13r,13a â,13br,-

13câ,14r,14a â)-1,2,3,4,4a ,5,5a ,5b ,5c,6,13,13a ,13b ,13c,14,-

14a -Hexa d eca h yd r o-1,4-eth en o-5,14:6,13-d im eth a n o-7,12-

d im e t h oxy-5b ,13b -d im e t h yln a p h t h o[2′′,3′′:3′,4′]cyclo-

bu ta [1′,2′:3,4]cyclobu t[1,2-b]a n th r a cen e-2,3-tr a n s-d ica r -

boxyla te (28b). A solution of ketal 25b (4.61 g, 8.77 mmol)^18a

in formic acid (30 mL) and THF (40 mL) was stirred for 18 h

at 25 °C. The formic acid was removed by extraction with

water and saturated NaHCO₃. Evaporation of the organic

extracts gave ketone 26b (3.87 g, 92%). This material was

unstable at elevated temperatures and could not be fully

(1r,4r,4a â,5r,5a â,5b r,5câ,6r,13r,13a â,13b r,13câ,14r,-

14a â)-1,4,4a ,5,5a ,5b ,5c,6,13,13a ,13b ,13c,14,14a -Te t r a -

d e ca h yd r o-1,4-e t h a n o-5,14:6,13-d im e t h a n o-5b ,13b -d i-

m eth yl-2,3-bis(m eth ylen e)n a p h th o[2′′,3′′:3′,4′]cyclobu ta -

[1′,2′:3,4]cyclobu t[1,2-b]a n th r a cen e-7,12-d ion e (8f). To a

stirred solution of 8b (151 mg, 0.299 mmol) in THF/MeCN (6:

8) was added, dropwise over 5 min, CAN (491 mg, 0.9 mmol)

in water (3 mL). The reaction mixture was then stirred for a

further 25 min at 25 °C, during which time 8f precipitated as

a yellow solid. After filtration, the filtrate was extracted with

CH₂Cl₂(2 × 20 mL) and the combined organic extracts were

washed with water (2 × 20 mL), dried, filtered, and evaporated

under reduced pressure to give a second crop of 8f (total

combined yield 135 mg, 95%) which was further purified by

chromatography (silica, EtOAc:hexane 20:80): mp decomposed

above 220 °C (from hexane); ¹H NMR (300 MHz, CDCl₃) δ

(ppm) 0.88 (s, 6H), 1.43-1.50 (overlapping multiplets, 6H),

1.62 (d, J ) 10.0 Hz, 1H), 1.84 (d, J ) 8.7 Hz, 2H), 1.88 (s,

2H), 1.97 (d, J ) 9.3 Hz, 1H), 2.11 (s, 2H), 2.32 (br s, 2H), 3.53

(s, 2H), 4.68 (s, 2H), 5.22 (s, 2H), 7.65-7.69 (m, 2H, 8.03-

8.06 (m, 2H); ¹³C NMR (75 MHz, CDCl₃) δ (ppm) 9.53, 22.26,

31.06, 39.41, 40.62, 41.43, 43.88, 44.99, 48.59, 53.81, 102.68,

126.24, 133.12, 133.25, 150.77, 154.05, 181.92. Anal. Calcd

for C₃₄H₂₄O₂: C, 86.04; H, 7.22. Found: C, 85.90; H, 7.35.

characterized: IR ν_max(Nujol) 1770 cm^-1

.

A solution of the ketone 26b (3.81 g, 7.97 mmol) and

dimethyl fumarate (1.18 g, 8.21 mmol) in dry toluene (14.0

mL) was refluxed for 18 h. Removal of the solvent under

reduced pressure and recrystallization of the residue from hot

MeOH gave pure 28b (4.38 g, 93%): mp 250-251 °C (from

1

MeOH); H NMR (300 MHz, CDCl₃) δ (ppm) 0.84 (d, J ) 2.6

Hz, 6H), 1.07 (d, J ) 10.8 Hz, 1H), 1.41 (dd, J ) 2.3, 8.5 Hz,

1H), 1.62 (d, J ) 9.0 Hz, 2H), 1.84 (d, J ) 9.5 Hz, 1H), 1.89 (s,

2H), 1.97 (s, 2H), 2.01 (s, 2H), 2.13 (s, 2H), 2.24 (d, J ) 10.8

Hz, 1H), 2.70 (dd, J ) 3.1, 5.4 Hz, 1H), 3.03-3.05 (m, 1H),

3.08-3.10 (m, 2H), 3.59 (d, J ) 3.1 Hz, 2H), 3.62 (s, 3H), 3.68

(s, 3H), 3.95 (d, J ) 5.1 Hz, 6H), 6.08 (br t, J ) 7.2 Hz, 1H),

6.26 (br t, J ) 7.4 Hz, 1H), 7.41-7.45 (m, 2H), 8.06-8.09 (m,

2H); ¹³C NMR (75 MHz, CDCl₃) δ (ppm) 9.68, 31.01, 37.15,

37.22, 40.56, 41.07, 41.50, 42.57, 42.79, 43.93, 43.96, 46.13,

46.88, 47.27, 50.61, 52.05, 52.18, 54.16, 61.81, 61.93, 121.98,

124.63, 127.79, 132.13, 134.35, 135.25, 135.32, 144.14, 173.95,

174.43. Anal. Calcd for C₃₈H₄₂O₆: C, 76.74; H, 7.12. Found:

C, 76.47; H, 7.25.

(1r,4r,4a â,5r,5a â,5b r,5câ,6r,13r,13a â,13b r,13câ,14r,-

14a â)-1,4,4a ,5,5a ,5b ,5c,6,13,13a ,13b ,13c,14,14a -Te t r a -

d e c a h y d r o -1 ,4 -e t h a n o -5 ,1 4 :6 ,1 3 -d i m e t h a n o -7 ,1 2 -

d im eth oxy-5b,13b-d im eth yl-2,3-bis(m eth ylen e)n a p h th o-

[2′′,3′′:3′,4′]cyclob u t a [1′,2′:3,4]cyclob u t [1,2-b]a n t h r a -

cen e (8b). A solution of 28b (4.3 g, 7.25 mmol) in EtOAc (150

mL) was catalytically hydrogenated at 1 atm and 25 °C using

5% Pd/C (300 mg) until the uptake of hydrogen had ceased.

Filtration and evaporation under reduced pressure gave the

saturated diester 29b (4.2 g, 96%), which was not purified

further: ¹H NMR (300 MHz, CDCl₃) δ (ppm) 0.93 (d, J ) 2.3

Hz, 6H), 1.23-1.65 (overlapping multiplets, 8H), 1.88 (d, J )

9.8 Hz, 2H), 1.96 (s, 2H), 2.03 (d, J ) 11.0 Hz, 2H), 2.05 (d, J

) 12.1 Hz, 2H), 2.16 (s, 2H), 3.08 (br s, 2H), 3.62 (d, J ) 3.3

Hz, 2H), 3.65 (s, 3H), 3.68 (s, 3H), 3.95 (s, 3H), 3.98 (s, 3H),

7.42-7.45 (m, 2H), 8.06-8.09 (m, 2H).

Dim eth yl (2ar,3â,8â,8ar)-2a,3,8,8a-Tetr ah ydr o-3,8-m eth -

a n ocyclobu ta [b]n a p h th a len e-1,2-d ica r boxyla te (19c). A

magnetically stirred solution of benzonorbornadiene, 10c (27.0

g, 0.19 mol), DMAD (27.5 g, 0.193 mol), and RuH₂CO(PPh₃)₃

(0.6 g, 0.5 mmol) in benzene (200 mL) was refluxed under an

argon atmosphere for 18 h. Ethanol was added to the cooled

reaction mixture, and the precipitated material was collected

and recrystallized from ethanol to give the ester 19c (50.3 g,

90%): mp 94-95 °C (from methanol); ¹H NMR (300 MHz,

CDCl₃) δ (ppm) 1.77 (s, 2H), 2.75 (s, 2H), 3.27 (s, 2H), 3.85 (s,

6H), 7.10 (m, 2H), 7.24 (m, 2H). Anal. Calcd for C₁₇H₁₆O₄:

C, 71.82; H, 5.67. Found: C, 72.06; H, 5.78.

Dim et h yl (1r,4r,4a â,4b r,4câ,5r,10r,10a â,10b r,10câ)-

1 ,4 ,4 a ,4 b ,4 c ,5 ,1 0 ,1 0 a ,1 0 b ,1 0 c -D e c a h y d r o -1 ,4 :5 ,1 0 -

dim eth an oben zo[3′,4′]cyclobu ta[1′,2′:3,4]cyclobu ta[1,2-b]-

n a p h th a len e-4b,10b-d ica r boxyla te (20c). A solution of 19c

(50.0 g, 0.176 mol) in quadricyclane (20.0 g, 0.217 mol) was

refluxed under an argon atmosphere for 18 h. Acetone (25

mL) was added to the cooled solution, and the resulting

precipitate was collected and recrystallized from acetone to

give 20c (57.2 g, 86.4%): mp 156-157 °C; ¹H NMR (300 MHz,

CDCl₃) δ (ppm) 1.15 (d, J ) 9.9 Hz, 1H), 1.57 (d, J ) 10.6 Hz,

1H), 1.92 (d, J ) 9.8 Hz, 1H), 2.07 (s, 2H), 2.30 (s, 2H), 2.35

(d, J ) 10.4 Hz, 1H), 2.86 (s, 2H), 3.32 (s, 2H), 3.80 (s, 6H),

6.05 (t, J ) 1.6 Hz, 2H), 7.09 (m, 2H), 7.20 (m, 2H). Anal.

Calcd for C₂₄H₂₄O₄: C, 76.57; H, 6.43. Found: C, 76.78; H,

6.60.

To an ice cold slurry of LiAlH₄(600 mg, 15.5 mmol) in

anhydrous THF (25 mL) was added 29b (4.2 g, 7.05 mmol) in

THF (125 mL), and the resulting reaction mixture was refluxed

for 24 h. Successive additions of water (0.7 mL), 15% NaOH

(0.7 mL), and more water (2.1 mL) to the cooled reaction

mixture, followed by filtration and evaporation under reduced

pressure, gave the diol 30b (3.5 g, 92%) which was not purified

further: IR, ν_max(Nujol) 3250 (br, OH) cm^-1

.

To a solution of 30b (3.5 g, 6.47 mmol) in anhydrous pyridine

(60 mL) cooled to -5 °C was added p-toluenesulfonyl chloride

(3.43 g, 17.97 mmol) in pyridine (25 mL). After addition was

completed the reaction mixture was stored at -5 °C for 3.5 d

and then poured on to ice and extracted with CH₂Cl₂(3 × 100

mL). The combined organic extracts were washed with 1 M

HCl (5 × 75 mL) and saturated NaHCO₃and dried, and the

solvent was removed under reduced pressure to give the

ditosylate 31b (5.3 g, 97%) which was not purified further.

To a solution of 31b (5.3 g, 6.24 mmol) in anhydrous DMSO

was carefully added t-BuOK (2.5 g, 20.35 mmol). After being

stirred at 25 °C for 19 h, the reaction mixture was poured onto

ice and extracted with CH₂Cl₂(3 × 120 mL). The organic

extracts were successively washed with water (2 × 75 mL) and

brine (6 × 75 mL), to remove the DMSO. The combined

(1r,4r,4a â,4b r,4câ,5r,10r,10a â,10b r,10câ)-1,4,4a ,4b ,-

4c,5,10,10a ,10b ,10c-Deca h yd r o-1,4:5,10-d im et h a n o-4b ,-

10b-d im eth ylben zo[3′,4′]cyclobu ta [1′,2′:3,4]cyclobu ta [1,2-

b]n a p h th a len e (23c). To a solution of 20c (40.0 g, 0.106 mol)

in dry THF (300 mL) was added LiAlH₄(9.0 g, 0.240 mol) in

small portions. The mixture was refluxed for 18 h. To the

cooled reaction mixture were added successively water (9.0

mL), 15% NaOH (9.0 mL), and water (27.0 mL). The mixture

was then filtered, and the filtrate was dried and evaporated

under reduced pressure to give the diol 21c (30.5 g, 89%) which

was not purified further: IR ν_max(Nujol) 3250 cm^-1

.

5048 J . Org. Chem., Vol. 61, No. 15, 1996

Lawson et al.

To a cooled solution (-5 °C) of the diol 21c (30.0 g, 80.0

mmol) in dry pyridine (150 mL) was added slowly methane-

sulfonyl chloride (21.8 g, 0.190 mol). The resulting solution

was kept at -5 °C for 72 h, after which it was poured onto

crushed ice and then extracted with CH₂Cl₂(3 × 150 mL). The

organic extract was washed successively with 1 M HCl (750

mL) and saturated NaHCO₃(100 mL), then dried, and

evaporated to give the dimesylate 22c (31.0 g, 73%) which was

not purified.

A magnetically stirred mixture of the dimesylate 22c (30.0

g, 56.39 mmol) and LiAlH₄(4.5 g, 0.120 mol) in dry THF (300

mL) was refluxed for 48 h. Use of a workup procedure that

was identical to that described above for the synthesis of the

diol gave 23c (15.2 g, 93%): mp 113 °C (from EtOAc/pentane);

¹H NMR (300 MHz, CDCl₃) δ (ppm) 0.90 (s, 6H), 1.19 (d, J )

8.9 Hz, 1H), 1.40 (d, J ) 8.8 Hz, 1H), 1.64 (d, J ) 8.9 Hz, 1H),

1.65 (s, 2H), 1.82 (d, J ) 8.9 Hz, 1H), 1.89 (s, 2H), 2.76 (br s,

2H), 3.27 (s, 2H), 5.98 (t, J ) 1.8 Hz, 2H), 7.05 (m, 2H), 7.15

(m, 2H). Anal. Calcd for C₂₂H₂₄: C, 91.61; H, 8.39. Found:

C, 91.52; H, 8.52.

(1r,4r,4a â,5r,5a â,5b r,5câ,6r,11r,11a â,11b r,11câ,12r,-

12a â)-1,4,4a ,5, 5a ,5b,5c,6,11,11a ,11b,11c,12,12a -Tetr a d eca -

h yd r o-8-a cet a m id o-1,4-et h a n o-5,12:6,11-d im et h a n o-5b,-

11b -d im et h yl-2,3-b is(m et h ylen e)n a p h t h o[2′′,3′′:3′,4′]cy-

clobu ta [1′,2′:3,4]cyclobu ta [1,2-b]n a p h th a len e (8d ). A so-

lution of 23c (14.0 g, 48.6 mmol) and 1,2,3,4-tetrachloro-5,5-

dimethoxycyclopentadiene (13.0 g, 50 mmol) in xylene (bp

138-141 °C) (50 mL) was refluxed for 18 h. Azeotropic

removal of the xylene, through addition of ethanol (75 mL),

gave a solid residue which was assumed to be 24c (22.5 g, 84%)

since its 300 MHz ¹H NMR spectrum revealed the complete

absence of the peak at 5.98 ppm due to the double-bond protons

of 23c.

Sodium metal (33.0 g, 1.45 mol) was added piecewise to a

refluxing solution of 24c (20.0 g, 36.2 mmol) in THF (100 mL)

and 2-propanol (400 mL). The resulting mixture was refluxed

for 17 h. Methanol (20 mL) was added to the cooled reaction

mixture followed by crushed ice (100 g). Extraction with CH₂-

Cl₂(3 × 150 mL) and evaporation of the organic extracts (after

washing with water and drying) gave a solid (12.5 g, 83%)

whose ¹H NMR spectrum revealed the presence of 25c: ¹H

NMR (300 MHz, CDCl₃) δ (ppm) 0.80 (s, 6H), 1.02 (d, J ) 10.7

Hz, 1H), 1.54 (d, J ) 9.2 Hz, 1H), 1.72 (d, J ) 9.2 Hz, 1H),

1.86 (s, 2H), 1.91 (s, 2H), 1.95 (br s, 2H), 2.01 (s, 2H), 2.28 (d,

J ) 10.7 Hz, 1H), 2.86 (br s, 2H), 3.06 (s, 3H), 3.13 (s, 3H),

3.20 (s, 2H), 6.03 (t, J ) 1.8 Hz, 2H), 7.06 (m, 2H), 7.14 (m,

2H).

To a suspension of LiAlH₄(1.52 g, 40 mmol) in anhydrous

THF (50 mL) was added a solution of 29c (10.0 g, 20.7 mmol)

in THF (100 mL), and the mixture was refluxed for 18 h. To

the chilled reaction mixture were added water (1.5 mL), 15%

NaOH (1.5 mL), and more water (4.5 mL) successively. The

mixture was then filtered, and the filtrate was dried over Na₂-

SO₄and evaporated under reduced pressure to give the diol

30c (8.6 g, 91%) which was not further purified.

To a cooled solution (-5 °C) of the diol 30c (8.5 g, 19.8 mmol)

in dry pyridine (120 mL) was added acetic anhydride (90 mL).

The resulting solution was stirred at 25 °C for 18 h and then

for 1 h at 60 °C. To the chilled reaction mixture was added

methanol (50 mL). The solution was evaporated, and the

residue was extracted with CH₂Cl₂(3 × 150 mL). The organic

extract was washed successively with 1 M HCl (750 mL) and

saturated NaHCO₃(100 mL), then dried, and evaporated to

give the diacetate 33 (9.86 g, 97%) which was not purified.

Cu(NO₃)₂‚2.5H₂O (3.0 g, 12.4 mmol) was added to a solution

of 33 (9.86 g, 19.2 mmol) in CH₂Cl₂(30 mL) and acetic

anhydride (40 mL). The reaction mixture was magnetically

stirred for 18 h at 25 °C. The mixture was poured into ice (50

g) and ammonia (15 M, 60 mL). The resulting dark blue

solution was extracted with CH₂Cl₂(3 × 150 mL), washed with

water (3 × 50 mL), dried over anhydrous Na₂SO₄, and filtered

and the solvent was evaporated to give crude 35 (10.2 g, 81%).

Compound 35 (10.2 g, 18.2 mmol) and zinc powder (12.0 g,

0.185 mol) in acetic acid (17 M, 50 mL) and acetic anhydride

(6 mL) were refluxed for 18 h under an argon atmosphere. The

resulting white mixture was cooled to 25 °C, neutralized with

ammonia (15 M, 60 mL), extracted with CH₂Cl₂(2 × 100 mL),

washed with water (2 × 100 mL), and dried, and the solvent

was evaporated to give the crude amide 37 (9.5 g, 91%).

A solution of 37 (9.5 g, 16.6 mmol) and LiBH₄(0.8 g, 34

mmol) in dry THF (75 mL) was stirred at 25 °C for 5 d. Acetic

acid (5 M) was then carefully added until foaming had ceased.

The solution was extracted with CH₂Cl₂(3 × 100 mL), washed

with saturated NaHCO₃(3 × 100 mL), and dried, and the

solvent was removed under reduced pressure to give crude 39

(5.8 g, 72%).

To a cooled (-5 °C) solution of the diol 39 (5.8 g, 11.9 mmol)

in dry pyridine (50 mL) was added p-toluenesulfonyl chloride

(4.0 g, 21 mmol), and the resulting mixture was maintained

at -5 °C for 36 h. The reaction was then quenched with

crushed ice, and the solution was extracted with CH₂Cl₂(3 ×

100 mL). The combined organic extracts were washed suc-

cessively with 1 M HCl (3 × 100 mL) and saturated NaHCO₃

(100 mL) before being dried and concentrated under reduced

pressure to give the ditosylate 41 (8.3 g, 88%) which was not

purified.

To a solution of the ditosylate 41 (8.3 g, 10.4 mmol) in dry

DMSO (75 mL) was added t-BuOK (3.4 g, 30 mmol). The

mixture was then stirred at 25 °C for 18 h. Ice water was

added, and the product was extracted with CH₂Cl₂(3 × 100

mL). The combined organic extracts were washed with water

(2 × 100 mL) and brine (3 × 50 mL) to remove all traces of

DMSO and dried, and the solvent was removed under reduced

pressure. The residue was then chromatographed (silica,

EtOAc/hexane 30:70) to give the pure diene 8d (3.2 g, 68%):

mp 210 °C (from EtOAc/pentane); ¹H NMR (300 MHz, CDCl₃)

δ (ppm) 0.87 (s, 6H), 1.44 (br d, J ) 11.6 Hz, 2H), 1.46 (s, 2H),

1.50-1.55 (m, 2H), 1.72 (d, J ) 9.2 Hz, 1H), 1.85 (s, 2H), 1.87

(br d, J ) 11.6 Hz, 2H), 1.91 (s, 2H), 1.96 (d, J ) 11.0 Hz, 1H),

2.09 (s, 2H), 2.12 (s, 3H), 2.30 (s, 2H), 3.16 (br s, 2H), 4.67 (s,

2H), 5.22 (s, 2H), 7.05 (br s, 2H), 7.12 (br s, 1H), 7.39 (br s,

1H); ¹³C NMR (125 MHz, CS₂:acetone-d₆1:1) δ (ppm) 10.25,

23.18, 24.27, 28.58, 30.01, 30.44, 31.04, 31.93, 40.10, 41.53,

43.34, 44.30, 44.38, 44.75, 45.87, 45.89, 51.51, 51.77, 103.37,

113.44, 116.89, 121.04, 137.74, 142.95, 148.48, 151.02, 167.47.

Anal. Calcd for C₃₂H₃₇NO‚H₂O: C, 91.61; H, 8.39. Found: C,

91.52; H, 8.52.

A solution of the ketal 25c (12.0 g, 28.8 mmol) in formic

acid (100 mL) and THF (50 mL) was stirred for 18 h at 25 °C.

The formic acid was removed by extraction with water and

saturated NaHCO₃. Evaporation of the organic extracts gave

the ketone 26c as a fine white powder (9.6 g, 90%). This

material was unstable at elevated temperatures and could not

be fully characterized: IR ν_max(Nujol) 1780 cm^-1

.

The preparation of 28c was achieved directly from 26c,

without isolation of the intermediate diene 27c. Thus, a

solution of the ketone 26c (9.5 g, 25.84 mmol) and dimethyl

fumarate (4.0 g, 26.6 mmol) in toluene (50 mL) was refluxed

for 18 h. The solvent was then removed under reduced

pressure to give the diester 28c (11.8 g, 94%) which was not

purified further: ¹H NMR (300 MHz, CDCl₃) δ (ppm) 0.78 (s,

3H), 0.79 (s, 3H), 1.07 (d, J ) 10.8 Hz, 1H), 1.58-1.71

(overlapping multiplets, 6H), 1.85 (s, 2H), 1.88 (s, 2H), 1.96

(d, J ) 14.8 Hz, 2H), 2.24 (d, J ) 10.5 Hz, 1H), 3.09 (s, 2H),

3.18 (d, J ) 2.8 Hz, 2H), 3.62 (s, 3H), 3.69 (s, 3H), 6.09 (t, J )

7.2 Hz, 1H), 6.27 (t, J ) 7.4 Hz, 1H), 7.05 (m, 2H), 7.13 (m,

2H).

Compound 28c (11.0 g, 22.7 mmol) in ethyl acetate (200 mL)

was hydrogenated at 1 atm and 25 °C using 10% Pd/C (200

mg) until uptake of H₂had ceased. Standard workup proce-

dures gave the saturated diester 29c as colorless needles (10.5

g, 95%): ¹H NMR (300 MHz, CDCl₃) δ (ppm) 0.86 (s, 3H), 0.87

(s, 3H), 1.43 (d, J ) 11.8 Hz, 1H), 1.24-1.76 (overlapping

multiplets, 8H), 1.89 (s, 2H), 1.91 (s, 2H), 2.03 (d, J ) 11.4

Hz, 2H), 2.08 (d, J ) 12.7 Hz, 1H), 3.08 (s, 2H), 3.20 (d, J )

2.6 Hz, 2H), 3.66 (s, 3H), 3.68 (s, 3H), 7.05 (m, 2H), 7.13 (m,

2H).

(1r,4r,4a â,9r,9a â,10r)-1,2,3,4,4a ,9,9a ,10-Octa h yd r o-1,4-

et h a n o-2,3-tr a n s-b is(a cet oxym et h yl)-9,10-m et h a n oa n -

th r a cen e (32). A solution of 17c (7.27 g, 27.1 mmol) in acetic

anhydride (90 mL) and pyridine (180 mL) was stirred at 25

°C for 22 h and then heated at 80 °C for 2 h. The reaction

mixture was cooled to 0 °C, and the excess acetic anhydride

was quenched by the slow addition of methanol (40 mL) over

“Ball and Chain” Systems Based on C₆₀

J . Org. Chem., Vol. 61, No. 15, 1996 5049

40 min. The solvent volume was reduced in vacuo to ∼100

mL, and the resulting solution was poured onto ice (300 g)

and 1 M HCl (200 mL) and extracted with CH₂Cl₂(3 × 100

mL). The organic extracts were combined, washed with 1 M

HCl (6 × 200 mL), water (200 mL), and saturated NaHCO₃(2

× 200 mL), and dried over anhydrous Na₂SO₄. The solvent

was evaporated under reduced pressure and then under high

vacuum to give 32 as a clear oil (9.85 g, 98%) which was

recrystallized from hexane: mp 80 °C; ¹H NMR (300 MHz,

CDCl₃) δ (ppm) 1.20-1.52 (m, 4H), 1.55-1.67 (m, 4H), 1.78-

1.90 (m, 3H), 2.03 (s, 3H), 2.06 (s, 3H), 2.26 (d, J ) 10.0 Hz,

1H), 3.15 (br s, 1H), 3.20 (br s, 1H), 3.82 (dd, J ) 8.7, 10.9 Hz,

1H), 3.97 (dd, J ) 6.7, 10.9 Hz, 1H), 4.01-4.15 (m, 2H), 7.03

(dd, J ) 3.1, 5.1 Hz, 2H), 7.12 (m, 2H); IR ν_max(Nujol) 3030,

1735, 1490, 1250, 1245, 1230, 1030, 740 cm^-1. Anal. Calcd

for C₁₉H₂₄O₂: C, 74.97; H, 7.66. Found: C, 75.23; H, 7.85.

(1r,4r,4a â,9r,9a â,10r)-1,2,3,4,4a ,9,9a ,10-Octa h yd r o-2,3-

tr a n s-bis(a cetoxym eth yl)-1,4-eth a n o-9,10-m eth a n o-6-n i-

tr oa n th r a cen e (34). Cu(NO₃)₂‚2.5H₂O (8.40 g, 34.7 mmol)

was added to a stirred solution of 32 (8.40 g, 22.8 mmol) in

acetic anhydride (80 mL) and CH₂Cl₂(40 mL) at 0 °C, and the

reaction mixture was stirred at 20 °C for 17 h. The reaction

mixture was poured onto a mixture of ice (300 g) and 15 M

NH₃(150 mL) and stirred for 30 min. The resulting solution

was extracted with CH₂Cl₂(3 × 100 mL). The organic layers

were combined and washed with saturated NaHCO₃(2 × 200

mL) and dried over anhydrous Na₂SO₄. The solvent was

evaporated under reduced pressure to give a yellow oil which

was subjected to column chromatography (silica, benzene/ethyl

acetate 80:20) to give 34 as a light yellow oil (9.30 g, 89%):

¹H NMR (300 MHz, CDCl₃) δ (ppm) 1.28-1.38 (m, 2H), 1.40

(m, 1H), 1.50 (m, 1H), 1.58-1.66 (m, 4H), 1.80 (m, 1H), 1.88

(m, 2H), 2.03 (s, 3H), 2.05 (s, 3H), 2.35 (d, J ) 10.5 Hz, 1H),

3.27 (s, 1H), 3.32 (s, 1H), 3.80 (m, 1H), 3.91-4.13 (m, 3H), 7.25

(m, 1H), 7.96 (m, 1H), 7.99 (s, 1H).

P₂O₅. The dried solid was dissolved in dry THF (100 mL) and

filtered through dry silica. The silica was washed with a

further portion of THF (200 mL). The solutions were combined

and evaporated under reduced pressure to give 38 as a clear

oil (19.9 g, 99%): ¹H NMR (300 MHz, CDCl₃) δ (ppm) 1.20-

1.70 (m, 8H), 1.78-1.84 (m, 3H), 2.04 (m, 2H), 2.14 (s, 3H),

2.23 (d, J ) 10.1 Hz, 1H), 3.07 (br s, 2H), 3.10 (s, 1H), 3.14 (s,

1H), 3.31-3.55 (m, 2H), 3.60-3.65 (m, 2H), 6.93-6.99 (m, 1H),

7.05 (d, J ) 7.8 Hz, 1H), 7.30-7.42 (m, 2H).

p-Toluenesulfonyl chloride (38.0 g, 0.200 mmol) was added

to an ice cold solution of 38 (19.9 g, 58.7 mmol) in pyridine

(150 mL). The reaction mixture was maintained at -5 °C for

36 h and then poured onto ice (500 g). The resulting mixture

was extracted with CH₂Cl₂(3 × 150 mL). The extracts were

combined, washed with 1 M HCl (5 × 250 mL) and saturated

NaHCO₃(2 × 250 mL), and dried over anhydrous Na₂SO₄. The

solvent was evaporated under reduced pressure to give 40 as

a yellow solid (33.5 g, 88%): ¹H NMR (300 MHz, CDCl₃) δ

(ppm) 1.07-1.53 (m, 8H), 1.68-1.85 (m, 3H), 2.11 (s, 3H), 2.42

(s, 3H), 2.44 (s, 3H), 3.00 (s, 1H), 3.08 (s, 1H), 3.72 (br d, J )

7.8 Hz, 2H), 3.91 (br d, J ) 7.8 Hz, 2H), 6.93-6.99 (m, 1H),

7.05 (d, J ) 8.2 Hz, 1H), 7.29-7.40 (m, 5H), 7.64-7.77 (m,

5H); IR ν_max(Nujol) 3280, 3030, 1660, 1595, 1350, 1170, 950,

760, 660 cm^-1

.

t-BuOK (23.0 g, 0.205 mol) was added to a stirred solution

of 40 (33.5 g, 51.3 mmol) in DMSO (400 mL). The reaction

mixture was stirred for 14 h and then poured onto ice (500 g)

and brine (500 mL). The resulting precipitate was filtered,

dissolved in CH₂Cl₂(200 mL), and washed with saturated

NaHCO₃(2 × 200 mL). The solution was dried over anhydrous

Na₂SO₄and evaporated under reduced pressure to give a

brown solid. This was subjected to column chromatography

(silica, chloroform/ethyl acetate/benzene 50:25:25) to give an

off-white solid (8.5 g) which was recrystallized from benzene

1

to give 7d as a white solid (6.50 g, 41%): mp 175 °C dec; H

(1r,4r,4a â,9r,9a â,10r)-1,2,3,4,4a ,9,9a ,10-Oct a h yd r o-6-

a ceta m id o-2,3-tr a n s-bis(a cetoxym eth yl)-1,4-eth a n o-9,10-

m eth a n oa n th r a cen e (36). Compound 34 (26.5 g, 64.1 mmol)

in ethyl acetate (250 mL) and ethanol (50 mL) was hydroge-

nated at 1 atm and 25 °C using 10% Pd/C (0.40 g) until uptake

of H₂had ceased. The catalyst was removed, and the filtrate

was evaporated under reduced pressure to give crude amine

as a brown oil (23.9 g, 97%). The crude product was used in

the next reaction: ¹H NMR (300 MHz, CDCl₃) δ (ppm) 1.31-

1.46 (m, 3H), 1.53-1.63 (m, 5H), 1.73-1.85 (m, 3H), 2.03 (s,

3H), 2.05 (s, 3H), 2.20 (d, J ) 10.0 Hz, 1H), 3.03 (s, 1H), 3.08

(s, 1H), 3.46 (br s, 2H), 3.81-3.86 (m, 1H), 3.94-4.13 (m, 3H),

6.34 (dd, J ) 1.9, 7.9 Hz, 1H), 6.54-6.57 (m, 1H), 6.86-6.92

(m, 1H); IR ν_max(thin film) 3440, 3360, 3210, 3010, 2940, 1835,

NMR (300 MHz, CDCl₃) δ (ppm) 1.53 (br d, J ) 8.8 Hz, 2H),

1.61 (d, J ) 10.0 Hz, 1H), 1.62 (s, 2H), 1.86 (br d, J ) 8.8 Hz,

2H), 2.13 (s, 3H), 2.26 (d, J ) 10.0 Hz, 1H), 2.54 (s, 2H), 3.18

(s, 1H), 3.20 (s, 1H), 4.71 (s, 2H), 5.21 (s, 2H), 6.96 (dd, J )

2.0, 7.7 Hz, 1H), 7.05 (d, J ) 7.7 Hz, 1H), 7.08 (br s, 1H), 7.42

(d, J ) 2.0 Hz, 1H); ¹³C NMR (75 MHz, CDCl₃) δ (ppm) 21.90,

21.96, 24.58, 40.80, 43.06, 43.31, 44.16, 46.24, 46.92, 103.04,

103.16, 113.28, 116.67, 120.36, 135.09, 146.84, 150.21, 150.32,

151.42, 168.10. Anal. Calcd for C₂₁H₂₃NO: C, 82.59; H, 7.59;

N, 4.59. Found: C, 82.80; H, 7.72; N, 4.34.

(1r,4r,4aâ,9r,9aâ,10r)-1,4,4a,9,9a,10-Hexah ydr o-6-am in o-

1,4-e t h a n o -9,10-m e t h a n o -2,3-b is (m e t h y le n e )a n t h r a -

cen e (42). A suspension of 7d (1.00 g, 3.27 mmol) and KOH

(5.30 g, 94 mmol) in methanol (28 mL) and water (5 mL) was

refluxed, under an argon atmosphere, for 24 h. The reaction

mixture was cooled to 25 °C, and water (50 mL) was added.

The resulting precipitate was filtered off and washed with

water. The precipitate was dissolved in CH₂Cl₂(100 mL),

washed with saturated NaHCO₃(100 mL), and dried over

anhydrous Na₂SO₄. The solvent was evaporated under re-

duced pressure to give a white solid which was extracted into

boiling hexane (8 × 100 mL) and filtered. The filtrate fractions

were combined, and the solvent volume was reduced under

reduced pressure to ca. 20 mL. The resulting white precipitate

1615, 1595, 1240, 1030, 905, 730 cm^-1

.

Acetic anhydride (7.0 mL, 74.0 mmol) was added to a stirred

solution of the crude amine (23.9 g, 62.3 mmol) in CH₂Cl₂(50

mL), and stirring was continued for 30 min. Saturated

NaHCO₃(250 mL) was added, and the resulting mixture was

stirred for a further 2 h. The layers were separated, and the

aqueous layer was extracted with a further portion of CH₂Cl₂

(50 mL). The organic layers were combined, washed with

brine (200 mL), and dried over anhydrous Na₂SO₄. The

solvent was evaporated under reduced pressure to give a

brown oil. The crude product was subjected to column chro-

matography (silica, benzene/ethyl acetate 60:40) to give 36 as

a white solid (24.9 g, 94%): mp 84-85 °C; ¹H NMR (300 MHz,

CDCl₃) δ (ppm) 1.21-1.50 (m, 4H), 1.52-1.59 (m, 4H), 1.77-

1.83 (m, 3H), 2.02 (s, 3H), 2.04 (s, 3H), 2.09 (s, 3H), 2.22 (d, J

) 9.9 Hz, 1H), 3.09 (s, 1H), 3.12 (s, 1H), 3.72-3.83 (m, 1H),

3.91-4.13 (m, 3H), 6.88-7.04 (m, 2H), 7.48 (br d, J ) 3.0 Hz,

1H), 7.80 (br s, 1H); IR ν_max(Nujol) 3280, 3030, 1735, 1670,

1

was collected as 42 (0.46 g, 53%): mp 120 °C; H NMR (300

MHz, CDCl₃) δ (ppm) 1.52 (br d, J ) 8.2 Hz, 2H), 1.59 (d, J )

9.8 Hz, 1H), 1.63 (s, 2H), 1.87 (br d, J ) 8.2 Hz, 2H), 2.24 (d,

J ) 9.8 Hz, 1H), 2.54 (s, 2H), 3.12 (s, 2H), 3.33 (br s, 2H), 4.72

(s, 2H), 5.22 (s, 2H), 6.34 (dd, J ) 2.2, 7.8 Hz, 1H), 6.56 (d, J

) 2.2 Hz, 1H), 6.90 (d, J ) 6.90 Hz, 1H); ¹³C NMR (75 MHz,

CDCl₃) δ (ppm) 21.97, 40.90, 40.96, 43.37, 43.90, 43.99, 45.89,

46.98, 102.86, 102.92, 108.77, 111.32, 120.65, 141.36, 143.77,

150.47, 151.91. Anal. Calcd for C₁₉H₂₁N: C, 86.65; H, 8.04;

N, 5.32. Found: C, 86.65; H, 8.13; N, 5.28.

1600, 1230 cm^-1

. Anal. Calcd for C₂₅H₃₁NO₅: C, 70.57; H,

7.34; N, 3.29. Found: C, 70.34; H, 7.60; N, 3.35.

(1r,4r,4a â,9r,9a â,10r)-1,4,4a ,9,9a ,10-H exa h yd r o-6-a c-

eta m id o-1,4-eth a n o-9,10-m eth a n o-2,3-bis(m eth ylen e)a n -

th r a cen e (7d ). LiBH₄(3.00 g, 0.160 mol) was added to a

stirred solution of 36 (24.9 g, 58.6 mmol) in dry THF (580 mL)

at 0 °C. The reaction mixture was allowed to warm to 25 °C

and stirred for 6.5 d. The 5% acetic acid (150 mL) was added,

and the solvent was evaporated under reduced pressure to give

a white viscous oil which was dried under high vacuum over

(1r,4r,4aâ,9r,9aâ,10r)-1,4,4a,9,9a,10-Hexah ydr o-1,4-eth -

a n o-9,10-m et h a n o-6-(N,N,N-t r im et h yla m in o)-2,3-b is(m -

eth ylen e)a n th r a cen e Iod id e (43). A suspension of 42 (0.72

g, 2.73 mmol) and NaHCO₃(0.88 g, 10.5 mmol) in methanol

(30 mL) and methyl iodide (1 mL, 16 mmol) was refluxed for

21 h. A further portion of methyl iodide (1 mL, 16 mmol) was

then added, and refluxing was continued for a further 24 h.

The solvent was evaporated under reduced pressure and the

5050 J . Org. Chem., Vol. 61, No. 15, 1996

Lawson et al.

resulting white solid was dissolved in CH₂Cl₂(200 mL),

washed with saturated NaHCO₃(2 × 100 mL), and dried over

anhydrous MgSO₄. The solvent was evaporated under reduced

pressure to give a white solid which was recrystallized from

CH₂Cl₂/hexane to give 43 as a white solid (0.92 g, 78%): mp

156 °C; ¹H NMR (300 MHz, CDCl₃) δ (ppm) 1.55 (br d, J ) 8.3

Hz, 2H), 1.64 (d, J ) 10.3 Hz, 1H), 1.70 (s, 2H), 1.84 (br d, J

) 8.3 Hz, 2H), 2.33 (d, J ) 10.3 Hz, 1H), 2.57 (s, 1H), 2.60 (s,

1H), 3.29 (s, 1H), 3.43 (s, 1H), 3.93 (s, 9H), 4.72 (s, 1H), 4.73

(s, 1H), 5.21 (s, 2H), 7.28 (d, J ) 8.3 Hz, 1H), 7.45 (dd, J )

2.7, 8.3 Hz, 1H), 7.76 (d, J ) 2.7 Hz, 1H). Anal. Calcd for

C₂₂H₂₈NI‚¹/₂H₂O: C, 59.73; H, 6.60; N, 3.17. Found: C, 59.73;

H, 6.70; N, 3.15.

stirred for 30 min. Water (100 mL) was added, and the

resulting mixture was extracted with CH₂Cl₂(3 × 50 mL). The

organic layers were combined, washed with water (100 mL),

saturated NaHCO₃(100 mL), and brine (100 mL), and dried

over anhydrous Na₂SO₄. The solvent was evaporated under

reduced pressure to give a brown solid which was subjected

to column chromatography (silica, 60-80 °C, light petroleum

ether/ethyl acetate 70:30) to give 46 as a white powder (1.10

g, 80%) which was recrystallized from hexane: mp 166 °C; ¹H

NMR (300 MHz, CDCl₃) δ (ppm) 0.83 (s, 3H), 0.84 (s, 3H),

1.20-1.31 (m, 3H), 1.35-1.65 (m, 4H), 1.68-1.93 (m, 6H),

1.97-2.12 (m, 5H), 2.88 (s, 6H), 3.08 (s, 2H), 3.13 (br s, 2H),

3.66 (s, 3H), 3.68 (s, 3H), 6.43-6.48 (m, 1H), 6.70 (br s, 1H),

6.99-7.03 (m, 1H); IR ν_max(Nujol) 1740, 1620, 1580 cm^-1. Anal.

Calcd for C₃₄H₄₃NO₄: C, 77.09; H, 8.14; N, 2.64. Found: C,

77.20; H, 8.44; N, 2.55.

(1r,4r,4aâ,9r,9aâ,10r)-1,4,4a,9,9a,10-Hexah ydr o-1,4-eth -

a n o-9,10-m eth a n o-6-(N,N-d im eth yla m in o)-2,3-bis(m eth -

ylen e)a n th r a cen e (7e). 43 (0.82 g, 1.89 mmol) was added

portionwise to a stirred, ice cold suspension of LiAlH₄(0.53 g,

14 mmol) in THF (20 mL). The reaction mixture was heated

at reflux for 80 min and then cooled to 0 °C. The excess

reagent was quenched by the sequential addition of water (0.5

mL), 15% NaOH (0.5 mL), and then water (1.5 mL). The

mixture was filtered, and the solvent was evaporated under

reduced pressure to give a white solid which was crystallized

from methanol to give 7e as a white powder (0.417 g, 76%):

(1r,4r,4a â,5r,5a â,5b r,5câ,6r,11r,11a â,11b r,11câ,12r,-

12a â)-1,4,4a ,5,5a ,5b ,5c,6,11,11a ,11b ,11c,12,12a -Te t r a -

d e ca h yd r o-1,4-e t h a n o-5,12:6,11-d im e t h a n o-5b ,11b -d i-

m eth yl-8-(N,N-d im eth yla m in o)-2,3-bis(m eth ylen e)n a p h -

t h o[2′′,3′′:3′,4′]cyclob u t a [1′,2′:3,4]cyclob u t a [1,2-b]n a p h -

th a len e (8e). The reduction of 46 (1.00 g, 1.89 mmol) with

LiAlH₄(0.50 g, 13 mmol) in THF (20 mL) was performed

according to the procedure for 17c (see above). The crude

product 47 (0.86 g, 96%) was dried over P₂O₅, under vacuum,

and used in the next reaction: ¹H NMR (60 MHz, CDCl₃) δ

(ppm) 0.9 (s, 6H), 1.3-1.8 (m, 10H), 1.85-2.2 (m, 10H), 2.9 (s,

6H), 3.2 (br s, 4H), 3.3-3.7 (m, 6H), 6.5 (br d, lH), 6.7 (br d,

1

mp 152 °C; H NMR (300 MHz) δ (ppm) 1.51 (br d, J ) 8.1

Hz, 2H), 1.60 (br d, J ) 9.7 Hz, 1H), 1.64 (s, 2H), 1.87 (br d,

J ) 8.1 Hz, 2H), 2.25 (br d, J ) 9.7 Hz, 1H), 2.54 (br s, 2H),

2.88 (s, 6H), 3.14 (s, 1H), 3.15 (s, 1H), 4.70 (s, 2H), 5.20 (s,

2H), 6.40 (dd, J ) 2.4, 8.0 Hz, 1H), 6.70 (d, J ) 2.4 Hz, 1H),

6.99 (d, J ) 8.0 Hz, 1H); ¹³C NMR (75 MHz, CDCl₃) δ (ppm)

22.00, 40.96, 41.03, 41.42, 43.52, 43.96, 44.13, 45.81, 47.35,

102.81, 106.69, 109.33, 120.46, 139.61, 149.15, 150.54, 151.64.

Anal. Calcd for C₂₁H₂₅N: C, 86.55; H, 8.65; N, 4.81. Found:

C, 86.28; H, 8.52; N, 4.77.

1H), 7.0 (br d, 1H); IR ν_max(Nujol) 3320, 1620, 1580 cm^-1

.

The bistosylation of 47 (0.86 g, 1.82 mmol) with p-toluene-

sulfonyl chloride (1.12 g, 5.89 mmol) in pyridine (20 mL) was

performed according to the procedure for 40 (see above). The

crude product 48 (1.20 g, 84%) was dried over P₂O₅, under

vacuum, and used in the next reaction: ¹H NMR (300 MHz,

CDCl₃) δ (ppm) 0.83 (s, 3H), 0.84 (s, 3H), 1.13-1.29 (m, 4H),

1.44-1.65 (m, 6H), 1.69-1.83 (m, 4H), 1.85-2.00 (m, 4H), 2.42

(s, 3H), 2.45 (s, 3H), 2.91 (s, 6H), 3.13 (s, 1H), 3.15 (s, 1H),

3.80-3.88 (m, 4H), 6.47 (dd, J ) 2.4, 8.0 Hz, 1H), 6.73 (d, J )

2.4 Hz, 1H), 7.02 (d, J ) 8.0 Hz, 1H), 7.30-7.36 (m, 4H), 7.71-

7.77 (m, 4H).

The bisdehydrotosylation of 48 (1.10 g, 1.40 mmol) with

t-BuOK (1.0 g, 8.9 mmol) in DMSO (15 mL) was performed

according to the procedure for 7d (see above). The crude

product was subjected to column chromatography (silica,

benzene) and recrystallized from hexane to give 8e as a white

solid (0.296 g, 48%): ¹H NMR (300 MHz, CDCl₃) δ (ppm) 0.87

(s, 6H), 1.44 (br d, J ) 11.6 Hz, 2H), 1.46 (s, 2H), 1.48 (d, J )

11.0 Hz, 1H), 1.54 (d, J ) 9.2 Hz, 1H), 1.74 (d, J ) 9.2 Hz,

1H), 1.86 (s, 2H), 1.87 (d, J ) 11.6 Hz, 1H), 1.91 (s, 2H), 1.95

(d, J ) 11.0 Hz, 1H), 2.07 (s, 2H), 2.31 (s, 2H), 2.90 (s, 6H),

3.13 (s, 1H), 3.15 (s, 1H), 4.68 (s, 2H), 5.23 (s, 2H), 6.45 (dd, J

) 2.4, 8.0 Hz, 1H), 6.70 (d, J ) 2.4 Hz, 1H), 7.01 (d, J ) 8.0

Hz, 1H); ¹³C NMR (75 MHz, CDCl₃) δ (ppm) 9.73, 9.78, 22.32,

31.13, 39.30, 40.71, 41.30, 42.74, 43.59, 43.88, 43.97, 44.39,

45.03, 50.80, 51.30, 53.89, 102.55, 106.91, 109.45, 120.87,

Dim eth yl (1r,4r,4a â,5r,5a â,5br,5câ,6r,11r,11a â,11br,-

11câ,12r,12a â)-1,2,3,4,4a ,5,5a ,5b ,5c,6,11,11a ,11b ,11c,12,-

12a -Hexa d eca h yd r o-1,4-eth a n o-5,12:6,11-d im eth a n o-5b,-

11b -d im e t h y l-8-n it r o n a p h t h o [2′′,3′′:3′,4′]c y c lo b u t a -

[1′,2′:3,4]cyclob u t a [1,2-b]n a p h t h a len e-2,3-tr a n s-d ica r -

boxyla te (44). The nitration of 29c (4.65 g, 9.55 mmol) with

Cu(NO₃)₂‚2.5H₂O (2.40 g, 10.3 mmol) in acetic anhydride (95

mL) and CH₂Cl₂(40 mL) was performed according to the

procedure for 34 (see above). The crude product was subjected

to column chromatography (silica, benzene) and recrystallized

from hexane to give 44 as a white solid (4.63 g, 91%): mp 141

1

°C; H NMR (300 MHz, CDCl₃) δ (ppm) 0.85 (s, 3H), 0.87 (s,

3H), 1.19-1.24 (m, 2H), 1.40-1.47 (m, 3H), 1.56-1.59 (m, 1H),

1.62 (s, 1H), 1.75 (m, 1H), 1.82 (d, J ) 9.8 Hz, 1H), 1.86 (s,

1H), 1.89 (s, 4H), 2.01 (s, 1H), 2.04 (s, 1H), 2.05 (d, J ) 6.3

Hz, 1H), 2.11(m, 1H), 3.07 (m, 2H), 3.31 (br t, J ) 3.4 Hz, 2H),

3.64 (s, 3H), 3.67 (s, 3H), 7.23 (d, J ) 8 Hz, 1H), 7.97 (s, 1H),

7.98 (br d, J ) 8 Hz, 1H). Anal. Calcd for C₃₂H₃₇NO₆: C,

72.29; H, 7.01; N, 2.63. Found: C, 72.55; H, 7.26; N, 2.58.

Dim eth yl (1r,4r,4a â,5r,5a â,5br,5câ,6r,11r,11a â,11br,-

11câ,12r,12a â)-1,2,3,4,4a ,5,5a ,5b ,5c,6,11,11a ,11b ,11c,12,-

12a -Hexa d eca h yd r o-1,4-eth a n o-5,12:6,11-d im eth a n o-5b,-

11b -d im e t h yl-8-(N ,N -d im e t h yla m in o)n a p h t h o[2′′,3′′:

3′,4′]cyclobu ta [1′,2′:3,4]cyclobu ta [1,2-b]n a p h th a len e-2,3-

tr a n s-d ica r boxyla te (46). Compound 44 (4.63 g, 8.71 mmol)

in a mixture of ethyl acetate (150 mL) and ethanol (30 mL)

was hydrogenated at 1 atm and 25 °C using 5% Pd/C (100 mg)

until uptake of H₂had ceased. The catalyst was removed, and

the filtrate was evaporated under reduced pressure to give

crude 45 as a brown oil (4.27 g, 98%). The crude product was

used in the next reaction: ¹H NMR (300 MHz, CDCl₃) δ (ppm)

0.83 (s, 3H), 0.84 (s, 3H), 1.20-1.31 (m, 3H), 1.35-1.65 (m,

4H), 1.68-1.93 (m, 6H), 1.97-2.12 (m, 5H), 3.08 (s, 2H), 3.11

(br s, 2H), 3.66 (s, 3H), 3.68 (s, 3H), 4.40 (br s, 2H), 6.50-6.54

(m, 1H), 6.68 (br s, 1H,), 6.91-6.96 (m, 1H); IR ν_max(Nujol)

136.71, 149.06, 149.33, 150.93.

Anal.

Calcd for

C₃₂H₃₉N‚H₂O: C, 84.43; H, 9.07; N, 3.07. Found: C, 84.70;

H, 9.22; N, 3.12.

(1r4r,4a â,5r,5a â,5b r,5câ,6r,6a â,7r,10r,10â,11r,11a â,-

11br,11câ,12r,12a â)-1,4,4a ,5,5a ,5b,5c,6,6a ,7,10,10a ,11,11a ,-

11b,11c,12,12a -Octa d eca h yd r o-1,4:7,10-d ieth a n o-5,12:6,-

1 1 -d i m e t h a n o -5 b ,1 1 b -d i m e t h y l -2 ,3 ,8 ,9 -t e t r a k i s -

(m eth ylen e)n a p h th o[2′′,3′′:3′,4′]cyclobu ta [1′,2′:3,4]cyclob-

u ta [1,2-b]n a p h th a len e (9). A solution of 60 (10.0 g, 42.0

mmol)¹⁹and 1,2,3,4-tetrachloro-5,5-dimethoxycyclopentadiene

(25.0 g, 94.7 mmol) in xylene (bp 138-141 °C) (100 mL) was

refluxed for 18 h. Azeotropic removal of the xylene, through

addition of ethanol (100 mL), gave a solid residue which was

assumed to be 61 (32.1 g, 94%) since its 300 MHz ¹H NMR

spectrum revealed the complete absence of the peak at 6.01

ppm due to the double-bond protons of 60.

Sodium metal (25.0 g, 1.1 mol) was added piecewise to a

refluxing solution of 61 (10.0 g, 13.1 mmol) in THF (200 mL)

and 2-propanol (400 mL). The resulting mixture was refluxed

for 18 h. Methanol (50 mL) was added to the cooled reaction

mixture, followed by crushed ice (100 mL). Extraction with

CH₂Cl₂(3 × 150 mL) and evaporation of the organic extracts

3460, 3380, 1740 cm^-1

.

A slurry of 45 (1.30 g, 2.59 mmol) and NaBH₄(2.00 g, 31

mmol) in THF (16 mL) and ethanol (4 mL) was added dropwise

to an ice cooled, stirring solution consisting of 35% formalde-

hyde (4.0 mL, 22 mmol), 3 M H₂SO₄(6 mL), and THF (8 mL).

The dropping rate was controlled so that the reaction temper-

ature remained between 15 and 20 °C. After the addition was

complete, 2.5 M KOH (20 mL) was added and the solution

“Ball and Chain” Systems Based on C₆₀

J . Org. Chem., Vol. 61, No. 15, 1996 5051

(after washing with water and drying) gave the bisketal 62

(5.4 g, 85%) which was not purified further.

reflux for 2 h under an argon atmosphere. The catalyst was

remove by suction filtration, and the solvent was evaporated

under reduced pressure to give a yellow oil. Water (50 mL)

was added, and the resulting suspension was extracted with

CHCl₃(7 × 100 mL). The organic extracts were combined and

dried over anhydrous Na₂SO₄. The solvent was evaporated

under reduced pressure to give 53 as an off-white solid (0.70

g, 55% from 49): ¹H NMR (300 MHz, d₆-DMSO) δ (ppm) 0.89-

0.93 (m, 1H), 1.03-1.15 (m, 4H), 1.33 (d, J ) 9.0 Hz, 1H), 1.46

(s, 1H), 1.47 (s, 1H), 1.62-1.73 (m, 1H), 1.77 (br s, 2H), 2.12

(d, J ) 9.0 Hz, 1H), 2.83 (s, 1H), 2.88 (s, 1H), 3.05-3.40 (m,

4H), 4.10 (br s, 4H), 4.46 (br s, 2H), 6.38 (s, 2H).

A solution of bisketal 62 (5.2 g, 10.6 mmol) in formic acid

(50 mL) and THF (20 mL) was stirred for 18 h at 25 °C. The

formic acid was removed by extraction with water and

saturated NaHCO₃. Evaporation of the organic extracts gave

diketone 63 (3.85 g, 91%). This material was unstable at

elevated temperatures and could not be fully characterized:

IR ν_max(Nujol) 1770 cm^-1

.

A solution of the diketone 63 (3.5 g, 8.8 mmol) and dimethyl

fumarate (3.0 g, 20.8 mmol) in toluene (30 mL) was refluxed

for 18 h. The solvent was then removed under reduced

pressure to give the tetraester 64 (5.9 g, 94%) which was not

purified further.

A stirred solution of 53 (0.70 g, 2.23 mmol) and 1,10-

phenanthroline-5,6-dione (55) (0.42 g, 2.00 mmol) in THF (100

mL) was heated at reflux, under an argon atmosphere for 10

h. The solvent was evaporated under reduced pressure to give

a yellow solid which was recrystallized from ethyl acetate to

The tetraester 64 (5.5 g, 8.7 mmol) in ethyl acetate (100

mL) was hydrogenated at 1 atm and 25 °C using 10% Pd/C

(100 mg) until uptake of H₂had ceased. Standard workup

procedures gave the saturated tetraester 65 (5.5 g, 98%) whose

¹H NMR spectrum revealed the absence of two peaks (triplets)

at 6.14 and 6.38 ppm due to the double-bond protons.

A solution of 65 (5.5 g, 8.7 mmol) in THF (100 mL) was

added to a suspension of LiAlH₄(1.5 g, 39.5 mmol) in THF

(50 mL), and the mixture was refluxed for 18 h. To the chilled

reaction mixture were added water (1.5 mL), 15% NaOH (1.5

mL), and more water (4.5 mL) successively. The mixture was

then filtered, and the filtrate was evaporated under reduced

pressure to give the tetrol 66 (3.9 g, 86%) which was not

1

give 56 as a yellow solid (0.89 g, 91%): mp 224 °C; H NMR

(300 MHz, d₆-DMSO) δ (ppm) 1.30-1.70 (m, 8H), 1.77-1.86

(m, 3H), 2.42 (d, J ) 11.2 Hz, 1H), 2.60 (br s, 2H), 3.15-3.49

(m, 6H), 7.68 (dd, J ) 4.4, 8.2 Hz, 2H), 7.86 (s, 2H), 9.10 (d, J

) 4.4 Hz, 2H), 9.52 (d, J ) 8.2 Hz, 2H). Anal. Calcd for

C₃₁H₂₈N₄O₂‚³/₂H₂O: C, 72.21; H, 6.06; N, 10.87. Found: C,

72.28; H, 6.16; N, 11.02.

(1r,4r,4a â,5r,18r,18a â)-1,4,4a ,5,18,18a -Hexa h yd r o-2,3-

bis(m et h ylen e)-1,4-et h a n o-5,18-m et h a n on a p h t h o[2′′,3′′-

i]d ip yr id o[3,2-a :2′,3′-c]p h en a zin e (7g). The bistosylation

of 56 (0.87 g, 1.78 mmol) with p-toluenesulfonyl chloride (3.00

g, 15.7 mmol) in pyridine (50 mL) was performed according to

the procedure for 40 (see above). The reaction mixture was

poured onto ice (200 g), resulting in the formation of a white

precipitate. This was isolated by suction filtration and washed

with water (3 × 50 mL). The crude bistosylate 58 (1.26 g, 89%)

was dried over P₂O₅, under vacuum, and used in the next

reaction: ¹H NMR (300 MHz, CDCl₃) δ (ppm) 1.24-1.30 (m,

2H), 1.41-1.51 (m, 2H), 1.60 (s, 1H), 1.63 (s, 1H), 1.77-1.85

(m, 3H), 2.01 (s, 2H), 2.36 (s, 3H), 2.42 (d, J ) 11.2 Hz, 1H),

2.44 (s, 3H), 3.42 (s, 1H), 3.50 (s, 1H), 3.70-3.76 (m, 2H), 3.92-

3.97 (m, 2H), 7.23-7.36 (m, 4H), 7.59-7.67 (m, 4H), 7.76 (dd,

J ) 4.4, 8.2 Hz, 2H), 7.91 (s, 2H), 9.23 (d, J ) 4.4 Hz, 2H),

9.58 (d, J ) 8.2 Hz, 2H).

further purified: IR ν_max(Nujol) 3254 cm^-1

.

To a cooled (-5 °C) solution of the tetrol 66 (3.8 g, 7.3 mmol)

in dry pyridine (50 mL) was added p-toluenesulfonyl chloride

(5.6 g, 29.4 mmol). The resulting mixture was maintained at

-5 °C for 36 h. The reaction was then quenched with crushed

ice, and the solution was extracted with CH₂Cl₂(3 × 100 mL).

The combined organic extracts were washed successively with

1 M HCl (3 × 100 mL) and saturated NaHCO₃(100 mL) before

being dried and concentrated under reduced pressure to give

the tetratosylate 67 (7.5 g, 91%) which was not purified.

To a solution of the tetratosylate 67 (7.0 g, 6.2 mmol) in

dry DMSO (50 mL) was added t-BuOK (4.0 g, 36.8 mmol). The

mixture was then stirred at 25 °C for 18 h. Ice water was

added, and the product was extracted with CH₂Cl₂(2 × 100

mL). The combined organic extracts were washed with water

(3 × 100 mL) and brine (3 × 50 mL) to remove all traces of

DMSO and dried, and the solvent was removed under reduced

pressure. The residue was then chromatographed (silica,

EtOAc:hexane 30:70) to give pure tetraene 9 (1.4 g, 66%): mp

The bisdehydrotosylation of 58 (1.26 g, 1.57 mmol) with

t-BuOK (1.1 g, 9.8 mmol) in DMSO (10 mL) was performed

according to the procedure for 7e (see above). The crude

product was subjected to column chromatography (silica, CH₂-

Cl₂/methanol 98:2) and recrystallized from hexane to give 7g

1

as an orange solid (0.12 g, 17%): mp 208 °C; H NMR (300

225 °C dec; H NMR (300 MHz, CDCl₃) δ (ppm) 0.76 (s, 6H),

MHz, CDCl₃) δ (ppm) 1.63 (d, J ) 8.3 Hz, 2H), 1.84 (d, J )

10.5 Hz, 1H), 1.89 (s, 2H), 1.97 (d, J ) 8.3 Hz, 2H), 2.56 (d, J

) 10.5 Hz, 1H), 2.69 (s, 2H), 3.58 (s, 2H), 4.78 (s, 2H), 5.25 (s,

2H), 7.79 (dd, J ) 4.4, 8.2 Hz, 2H), 7.98 (s, 2H), 9.26 (d, J )

4.4 Hz, 2H), 9.63 (d, J ) 8.2 Hz, 2H); ¹³C NMR (75 MHz,

CDCl₃) δ (ppm) 22.05, 40.77, 43.10, 43.28, 46.88, 103.70,

119.02, 124.15, 128.00, 129.90, 133.87, 139.42, 142.80, 150.79,

151.77, 152.84; HRMS calcd for C₃₁H₂₄N₄452.2001, found

452.2032.

(1r,4r,4a â,5r,5a â,5b r,5câ,6r,11r,11a â,11b r,11câ,12r,-

12a â)-1,2,3,4,4a ,5,5a ,5b ,5c,6,11,11a ,11b ,11c,12,12a -H exa -

d eca h yd r o-9-a cet a m id o-2,3-tr a n s-b is(a cet oxym et h yl)-

5 b ,1 1 b -d i m e t h y l -8 -n i t r o -1 ,4 -e t h a n o -5 ,1 2 :6 ,1 1 -d i -

m eth a n on a p h th o[2′′,3′′:3′,4′]cyclobu ta [1′,2′:3,4]cyclobu ta -

[1,2-b]n a p h th a len e (50). The nitration of 37 (2.32 g, 4.06

mmol) with Cu(NO₃)₂‚2.5H₂O (1.08 g, 4.64 mmol) in acetic

anhydride (30 mL) and CH₂Cl₂(10 mL) was performed

according to the procedure for 34 (see above). The crude

product was subjected to column chromatography (silica, light

petroleum ether/ethyl acetate 50:50) and recrystallized from

CH₂Cl₂/ hexane to give 50 as a yellow solid (2.03 g, 81%): mp

170 °C; ¹H NMR (300 MHz, CDCl₃) δ (ppm) 0.87 (s, 6H), 1.15-

1.27 (m, 2H), 1.36-1.40 (m, 2H), 1.46 (s, 1H), 1.50 (s, 1H),

1.56-1.63 (m, 5H), 1.82 (s, 1H), 1.85-1.92 (m, 4H), 1.94 (s,

2H), 2.00 (s, 1H), 2.04 (s, 6H), 2.06 (s, 1H), 2.27 (s, 3H), 3.26

(s, 1H), 3.32 (s, 1H), 3.96-4.10 (m, 4H), 7.96 (s, 1H), 8.55 (s,

1H), 10.53 (br s, 1H). Anal. Calcd for C₃₆H₄₄N₂O₇‚¹/₂H₂O: C,

69.10; H, 7.25; N, 4.48. Found: C, 69.19; H, 7.50; N, 4.28.

(1r,4r,4a â,5r,5a â,5b r,5câ,6r,19r,19a â,19b r,19câ,20r,-

20a â)-1,2,3,4,4a ,5,5a ,5b ,5c,6,19,19a ,19b ,19c,20,20a -H exa -

1.42 (br d, J ) 9.9 Hz, 6H), 1.51 (s, 4H), 1.85 (m, 4H), 1.89 (d,

J ) 10.1 Hz, 2H), 1.91 (s, 4H), 2.01 (s 4H), 2.30 (s, 4H), 4.67

(s, 4H), 5.22 (s 4H). Anal. Calcd for C₃₄H₄₂: C, 90.61; H, 9.39.

Found: C, 90.38; H, 9.51.

(1r,4r,4a â,9r,9a â,10r)-1,2,3,4,4a ,9,9a ,10-Oct a h yd r o-7-

a ceta m id o-2,3-bis(a cetoxym eth yl)-6-n itr o-1,4-eth a n o-9,-

10-m eth a n oa n th r a cen e (49). The nitration of 36 (7.60 g,

17.8 mmol) with Cu(NO₃)₂‚2.5H₂O (5.30 g, 22.8 mmol) in acetic

anhydride (100 mL) was performed according to the procedure

for 34 (see above). The crude product was subjected to column

chromatography (silica, light petroleum ether/ethyl acetate 70:

30) and recrystallized from hexane to give the diasereometric

mixture of 49 as a yellow solid (6.93 g, 83%): mp 62-63 °C;

¹H NMR (300 MHz, CDCl₃) δ (ppm) 1.25-1.53 (m, 4H), 1.55-

1.67 (m, 4H), 1.80-1.91 (m, 3H), 2.04 (s, 3H), 2.05 (s, 3H), 2.25

(s, 3H), 2.33 (d, J ) 10.5 Hz, 1H), 3.22 and 3.27 (s, 1H), 3.27

and 3.31 (s, 1H), 3.70-3.83 (m, 1H), 3.94-4.10 (m, 3H), 7.95

and 7.98 (s, 1H), 8.55 and 8.59 (s, 1H), 10.53 and 10.56 (s,

1H). Anal. Calcd for C₂₅H₃₀N₂O₇‚¹/₂C₆H₁₄: C, 65.47; H, 7.26;

N, 5.45. Found: C, 65.72; H, 7.05; N, 5.50.

(1r,4r,4a â,5r,18r,18a â)-1,2,3,4,4a ,5,18,18a -Octa h yd r o-

2,3-bis(h ydr oxym eth yl)-1,4-eth an o-5,18-m eth an on aph th o-

[2′′,3′′-i]d ip yr id o[3,2-a :2′,3′-c]p h en a zin e (56). A stirred

suspension of 49 (1.89 g, 4.02 mmol) in hydrazine hydrate (40

mL) was heated at 100 °C for 13 h under argon atmosphere.

The solvent was evaporated under high vacuum to give 51 as

a yellow solid. The crude product was used in the next

reaction. ¹H NMR indicated complete loss of acetyl groups.

A solution of the crude 51 in hydrazine hydrate (11 mL, 0.23

mol) and ethanol (50 mL) over 5% Pd/C (0.10 g) was heated at

5052 J . Org. Chem., Vol. 61, No. 15, 1996

Lawson et al.

decah ydr o-2,3-bis(m eth ylen e)-5b,19b-dim eth yl-1,4-eth an o-

5 , 2 0 :6 , 1 9 -d i m e t h a n o n a p h t h o [ 2 ′ ′ ′ ′, 3 ′ ′ ′ ′:3 ′ ′ ′, 4 ′ ′ ′] -

cyclob u t a [1′′′,2′′′:3′′,4′′]cyclob u t a [1′′,2′′-i]d ip yr id o[3,2-a :

2′,3′-c]p h en a zin e (8g). The hydrolysis of 50 (2.53 g, 4.10

mmol) with hydrazine hydrate (50 mL) was performed accord-

ing to the procedure for 51 (see above). The crude product 52

was isolated as a yellow solid and not purified further. ¹H

NMR showed no acetyl groups.

The reduction of the crude 52 with hydrazine hydrate (10

mL, 21 mmol) in ethanol (50 mL) over 5% Pd/C (0.10 g) was

performed according to the procedure for 53 (see above). The

crude product 54 was isolated as a yellow solid (1.31 g, 69%

from 50) and not purified further: ¹H NMR (300 MHz, CDCl₃)

δ (ppm) 0.87 (s, 6H), 1.19-1.46 (m, 7H), 1.50-1.60 (m, 4H),

1.82-1.87 (m, 2H), 1.96 (s, 2H), 2.02-2.09 (m, 5H), 2.32 (br s,

4H), 2.71 (br s, 2H), 3.08 (br s, 2H), 3.52-3.61 (m, 4H), 6.52

(s, 2H).

The condensation of 54 (1.31 g, 2.82 mmol) and 1,10-

phenanthroline-5,6-dione (55) (0.59 g, 2.81 mmol) in THF (100

mL) was performed according to the procedure for 56 (see

above). The crude product was crystallized from ethyl acetate

to give 57 as a yellow solid (1.72 g, 96%) and not purified

further: ¹H NMR (300 MHz, CDCl₃) δ (ppm) 0.97 (s, 3H), 0.98

(s, 3H), 1.21-1.46 (m, 7H), 1.50-1.60 (m, 4H), 1.82-1.87 (m,

2H), 1.96 (s, 2H), 2.02 (s, 1H), 2.05-2.07 (m, 2H), 2.16 (s, 2H),

2.00-2.50 (br s, 2H), 3.52-3.61 (m, 6H), 7.78 (dd, J ) 4.4, 8.2

Hz, 2H), 8.01 (s, 2H), 9.25 (d, J ) 4.4 Hz, 2H), 9.64 (d, J ) 8.2

Hz, 2H).

Hz, 1H), 6.67 (br s, 1H), 6.97 (d, J ) 8.0 Hz, 1H); ¹³C NMR

(125.8 MHz, CDCl₃) δ (ppm) 22.31, 22.34, 39.14, 39.20, 41.1,

43.8, 44.0, 44.02, 45.5, 46.5, 47.3, 66.2, 106.7, 109.0, 120.5,

135.1, 135.3, 139.7, 139.90, 139.94, 141.34, 141.39, 141.8,

141.9, 142.1, 142.32, 142.38, 142.41, 142.89, 142.93, 143.4,

143.7, 144.49, 144.51, 144.54, 145.11, 145.18, 145.20, 145.27,

145.36, 145.56, 145.63, 146.01, 146.03, 146.28, 146.30, 147.43,

148.7, 151.9, 156.9, 158.4; FAB MS m/ z (rel intensity) 1012

(100, MH⁺), 720 (90, C₆₀⁺); MALDI FTMS⁴¹m/ z (rel intensity)

1012 (MH⁺, 100), 720 (C₆₀⁺, 7); HRMS (FAB) calcd for

C₈₁H₂₅N‚H⁺1012.2065, found 1012.2046.

1,4-Dim eth oxyn a p h th a len e 7-Bon d C₆₀Ad d u ct 2f. Fol-

lowing the general procedure, C₆₀(36 mg, 0.05 mmol), diene

7f (19.2 mg, 0.05 mmol), and toluene (10 mL) were used. Flash

chromatography (CS₂/toluene 9:1) gave the cycloadduct 2f as

dark brown crystals (20 mg, 36%): ¹H NMR (360 MHz, CDCl₃)

δ (ppm) 1.43 (br d, J ) 11.6 Hz, 1H), 1.66 (br d, J ) 8.4 Hz,

2H), 1.95 (d, J ) 11.6 Hz, 1H), 1.99 (d, J ) 8.4 Hz, 2H), 2.02

(br s, 2H), 2.36 (s, 2H), 2.95 (br s, 2H), 3.47 (s, 2H), 4.06 (s,

6H), 4.18 (s, 4H), 7.25 (dd, J ) 6.4, 3.4 Hz, 2H), 7.92 (dd, J )

6.4, 3.4 Hz, 2H); ¹³C NMR (90.6 MHz, CDCl₃) δ (ppm) 22.6,

23.6, 39.1, 41.8, 44.0, 46.5, 51.9, 56.9, 66.2, 121.3, 121.8, 124.4,

126.7, 135.09, 135.12, 139.9 (2C), 141.29, 141.31, 141.76,

141.78, 142.95, 142.03, 142.14, 142.3, 142.8, 142.9, 144.41,

144.43, 145.08, 145.10, 145.15, 145.17, 145.23, 145.46, 145.50,

146.0 (2C), 146.22, 146.24, 147.34; FAB MS m/ z (rel intensity)

1105 (20, MH⁺), 720 (100, C₆₀⁺).

Dip yr id op h en a zin e 6-Bon d C₆₀Ad d u ct 2g. Meth od A.

Following the general procedure, C₆₀(14.4 mg, 0.02 mmol),

diene 7g (9.04 mg, 0.024 mmol), and toluene (15 mL) were

used. Flash chromatography (toluene/chloroform 1:3) gave the

product 2g as dark brown crystals (5.6 mg, 24%). Compound

2g slowly decomposes during chromatography and on standing

in air and light in solution: ¹H NMR (500 MHz, CDCl₃/CS₂

1:1) δ (ppm) 1.86 (d, J ) 8.8 Hz, 2H), 2.06 (d, J ) 10.4 Hz,

1H), 2.13 (d, J ) 8.8 Hz, 2H), 2.22 (s, 2H), 2.76 (d, J ) 10.4

Hz, 1H), 3.17 (s, 2H), 3.60 (s, 2H), 4.0-4.2 (AB q, J ) 14.1 Hz,

4H), 7.80 (dd, J ) 8.2, 4.4 Hz, 2H), 8.06 (s, 2H), 9.27 (dd, J )

4.4, 1.7 Hz, 2H), 9.65 (dd, J ) 8.2, 1.7 Hz, 2H); ¹³C NMR

(CDCl₃/CS₂1:1) δ (ppm) 38.93, 42.92, 45.31, 45.62, 66.19,

119.22, 123.8, 127.71, 133.26, 135.04, 135.26, 139.52, 140.02,

141.39, 141.45, 141.87, 141.94, 142.12, 142.35, 142.46, 142.54,

142.9, 143.69, 144.50, 144.60, 145.13, 145.25, 145.29, 145.35,

145.64, 146.10, 146.30, 146.40, 147.50, 147.92, 151.90, 154.91,

156.99, 158.26; FAB MS m/ z (rel intensity) 1173 (28, MH⁺),

720 (100, C₆₀⁺); HRMS calcd for C₉₁H₂₄N₄‚H⁺1173.2079, found

1173.2089.

Meth od B. To a solution of C₆₀(69.3 mg, 0.09 mmol) in 15

mL of o-dichlorobenzene in a pressure tube was added diene

7g (29 mg, 0.064 mmol) in 5 mL of o-dichlorobenzene. The

solution was deoxygenated and the tube heated in an oil bath

at 120-125 °C for 17 h. After being cooled to 25 °C, the

reaction mixture was diluted by adding 20 mL of light

petroleum ether. After 1 h, the precipitate was collected by

filtration. The residue was dissolved in chloroform (25 mL),

and cyclohexane (50 mL) was added. The mixture was filtered,

and the filtrate was evaporated to give a brown solid. The

solid was further purified by being dissolved in a minimum

amount of chloroform (1 mL), followed by precipitation with

light petroleum ether, to give a brown solid. The yield was

25 mg (34%) of 2g identical to material prepared above.

An th r a cen e 6-Bon d C₆₀Ad d u ct 2h . Following the gen-

eral procedure, C₆₀(72 mg, 0.1 mmol), diene 7h (43.5 mg, 0.125

mmol), and toluene (65 mL) were used. Flash chromatography

(cyclohexane/chloroform 4:1) gave the cycloadduct 2h as dark

brown crystals (55.3 mg, 52%), which were somewhat light-

sensitive (¹O₂formation): ¹H NMR (500 MHz, CDCl₂CDCl₂/

CS₂2:1) δ (ppm) 1.90 (d, J ) 8.9 Hz, 2H), 2.00 (d, J ) 10.4

Hz, 1H), 2.18 (d, J ) 8.9 Hz, 2H), 2.25 (s, 2H), 2.71 (d, J )

10.4 Hz, 1H), 3.17 (s, 2H), 3.46 (s, 2H), 4.10 (d, J ) 14.1 Hz,

2H), 4.28 (d, J ) 14.1 Hz, 2H), 7.46 (dd, J ) 6.4, 3.2 Hz, 2H),

7.72 (s, 2H), 7.98 (dd, J ) 6.4, 3.2 Hz, 2H), 8.29 (s, 2H); ¹³C

NMR (125.8 MHz, CDCl₂CDCl₂/CS₂2:1) δ (ppm) 22.5, 39.2,

42.6, 44.0, 45.0, 46.2, 66.2, 117.5, 124.9, 125.7, 127.9, 131.1,

131.3, 135.1, 135.3, 139.97, 140.03, 141.40, 141.45, 141.85,

141.97, 142.17, 142.38, 142.44, 142.45, 142.93, 142.98, 143.45,

144.52, 144.59, 145.14, 145.25, 145.31, 145.40, 145.61, 145.63,

The bistosylation of 57 (1.70 g, 2.67 mmol) with p-toluene-

sulfonyl chloride (2.00 g, 10.5 mmol) in pyridine (20 mL) was

performed according to the procedure for 58 (see above). The

crude product 59 (2.13 g, 84%) was dried over P₂O₅, under

vacuum, and used in the next reaction: ¹H NMR (300 MHz,

CDCl₃) δ (ppm) 0.95 (s, 3H), 0.96 (s, 3H), 1.21-1.46 (m, 7H),

1.50-1.60 (m, 4H), 1.82-1.87 (m, 2H), 1.96 (s, 2H), 2.02 (s,

1H), 2.05-2.07 (m, 2H), 2.16 (s, 2H), 2.40 (s, 3H), 2.44 (s, 3H),

3.57 (s, 2H), 3.77-3.87 (m, 4H), 7.30 (d, J ) 8.2 Hz, 2H), 7.34

(d, J ) 8.2 Hz, 2H), 7.71 (d, J ) 8.2 Hz, 2H), 7.74 (d, J ) 8.2

Hz, 2H), 7.79 (dd, J ) 4.4, 8.2 Hz, 2H), 8.00 (s, 2H), 9.23 (d, J

) 4.4 Hz, 2H), 9.66 (d, J ) 8.2 Hz, 2H).

The bisdehydrotosylation of 59 (2.13 g, 2.25 mmol) with

t-BuOK (0.80 g, 7.1 mmol) in DMSO (10 mL) was performed

according to the procedure for 7e (see above). The crude

product was subjected to column chromatography (silica, CH₂-

Cl₂/methanol 98:2) and recrystallized from hexane to give 8g

1

as an orange solid (0.31 g, 23%): mp 270 °C; H NMR (300

MHz, CDCl₃) δ (ppm) 0.99 (s, 6H), 1.44-1.55 (m, 6H), 1.94 (s,

2H), 2.01 (d, J ) 10.3 Hz, 1H), 2.07-2.17 (m, 5H), 2.32 (s,

2H), 3.56 (s, 2H), 4.67 (s, 2H), 5.20 (s, 2H), 7.79 (dd, J ) 4.4,

8.2 Hz, 2H), 8.00 (s, 2H), 9.23 (d, J ) 4.4 Hz, 2H), 9.66 (d, J

) 8.2 Hz, 2H); ¹³C NMR (75 MHz, CDCl₃) δ (ppm) 9.84, 22.29,

31.20, 39.33, 40.68, 42.62, 43.81, 44.40, 45.05, 50.36, 54.25,

102.67, 119.52, 124.20, 127.31, 128.04, 133.91, 139.31, 142.80,

150.79, 151.77, 152.84; MALDI MS m/ z (rel intensity) 599 (M

+ 1, 100).

Gen er a l P r oced u r e for th e P r ep a r a tion of th e Ba ll-

a n d -Ch a in C₆₀Diels-Ald er Ad d u cts 2e-h a n d 3a ,b,d -

h . A solution of the diene 7e-h or 8a ,b,d -h in 5-10 mL of

toluene was added via syringe pump (2-6 h) to a solution of

C₆₀in toluene under reflux. After the addition was completed,

the reaction was maintained at reflux for an additional 1-2

h. The reaction mixture was cooled to 25 °C, concentrated to

a small volume, and purified by flash chromatography on silica

gel. Yields of adducts are based on isolated material, except

when the yield based on recovered C₆₀is also indicated.

Elemental analyses were generally unsatisfactory due to the

strong solvent inclusion properties and/or incomplete combus-

tion of these C₆₀derivatives.

N,N-Dim eth yla n ilin e 6-Bon d C₆₀Ad d u ct 2e. Following

the general procedure, C₆₀(137.8 mg, 0.19 mmol), diene 7e

(87.4 mg, 0.3 mmol), and toluene (50 mL) were used. Flash

chromatography on silica gel (toluene) afforded the product

2e as dark brown crystals (118.1 mg, 61%): ¹H NMR (500

MHz, CDCl₃) δ (ppm) 1.77 (d, J ) 9.0 Hz, 2H), 1.80 (d, J )

10.0 Hz, 1H), 2.01 (s, 2H), 2.04 (d, J ) 9.0 Hz, 2H), 2.44 (d, J

) 10.0 Hz, 1H), 2.89 (s, 6H), 2.97 (br s, 2H), 3.07 (br s, 1H),

3.09 (s, 1H), 4.0-4.2 (AB q, J ) 14.0 Hz, 4H), 6.32 (d, J ) 8.0

“Ball and Chain” Systems Based on C₆₀

J . Org. Chem., Vol. 61, No. 15, 1996 5053

146.07, 146.32, 146.35, 147.5, 148.9, 156.9, 158.5; FAB MS m/ z

(rel intensity) 1069 (30, MH⁺) 720 (100, C₆₀⁺); HRMS calcd

for C₈₇H₂₄‚H⁺1069.1956, found 1069.1949.

135.1, 135.2, 136.2, 139.85, 139.90, 141.3, 141.77, 141.83,

142.11, 142.22, 142.33, 142.52, 142.84, 142.87, 144.44, 144.48,

145.14, 145.20, 145.23, 145.5, 145.7, 146.0, 146.22, 146.26,

147.4, 148.3, 148.8, 157.4, 158.0; FAB MS m/ z (rel intensity)

1158 (75, MH⁺), 720 (100, C₆₀⁺); HRMS calcd for C₉₂H₃₉N‚H⁺

1158.3161, found 1158.3121.

1,4-Dim eth oxyben zen e 10-Bon d C₆₀Ad d u ct 3a . Fol-

lowing the general procedure, C₆₀(72.1 mg, 0.1 mmol), diene

8a (44.7 mg, 0.098 mmol), and toluene (50 mL) were used.

Flash chromatography (toluene/hexanes 1:9) gave C₆₀(29.9 mg,

41%). Further elution with toluene/hexanes (1:1) gave the

product 3a as dark brown crystals (73.0 mg, 63%, quantitative

based on consumed C₆₀): ¹H NMR (360 MHz, CS₂/CDCl₃2:1)

δ (ppm) 0.92 (s, 6H), 1.45 (dt, J ) 1.6, 9.3 Hz, 1H), 1.56 (br d,

J ) 11.1 Hz, 1H), 1.61 (br d, J ) 7.6 Hz, 2H), 1.69 (br d, J )

9.3 Hz, 1H), 1.72 (br s, 2H), 1.89 (s, 2H), 1.92 (s, 2H), 1.96 (br

d, J ) 7.5 Hz, 2H), 2.07 (br d, J ) 11.5 Hz, 1H), 2.11 (s, 2H),

2.82 (br s, 2H), 3.41 (s, 2H), 3.72 (s, 6H), 4.0-4.15 (AB q, J )

14.0 Hz, 4H), 6.46 (s, 2H); ¹³C NMR (125.8 MHz, CS₂/CDCl₃

2:1) δ (ppm) 9.63, 22.66, 30.64, 37.74, 38.97, 40.14, 43.36, 43.41,

43.95, 46.27, 49.81, 54.21, 55.33, 66.21, 108.46, 135.14, 135.16,

136.27, 139.88, 139.90, 141.31, 141.33, 141.80, 141.85, 142.12,

142.22, 142.34, 142.54, 142.83, 142.89, 144.47, 144.49, 145.16,

145.17, 145.19, 145.20, 145.25, 145.52, 145.71, 145.97, 145.98,

146.23, 146.27, 147.37, 147.47, 157.48, 158.00. Anal. Calcd

for C₉₂H₃₈O₂(1175.33): C, 94.02; H, 3.26. Found: C, 94.08;

H, 2.94.

1,4-Na p h th oqu in on e 10-Bon d C₆₀Ad d u ct 3f. Following

the general procedure, C₆₀(72 mg, 0.1 mmol), diene 8f (47.4

mg, 0.1 mmol), and toluene (75 mL) were used. Flash

chromatography (toluene/cyclohexane 1:1) gave the product 3f

as dark brown crystals (68.8 mg, 58%): ¹H NMR (360 MHz,

CDCl₃) δ (ppm) 0.94 (s, 6H), 1.50-1.72 (m, 6H), 1.74 (s, 2H),

1.96 (s, 2H), 1.95-2.0 (m, 1H), 2.05 (s, 2H), 2.11-2.16 (m, 1H),

2.16 (s, 2H), 2.86 (s, 2H), 3.57 (s, 2H), 4.05-4.2 (AB q, J )

14.1 Hz, 4H), 7.69 (dd, J ) 5.7, 3.3 Hz, 2H), 8.06 (dd, J ) 5.7,

3.3 Hz, 2H); ¹³C NMR (125.8 MHz, toluene-d₈) δ (ppm) 9.4,

22.7, 30.6, 37.9, 38.9, 41.2, 41.3, 43.5, 43.9, 46.2, 48.7, 54.2,

66.2, 125.8, 127.8, 128.7, 132.5, 133.0, 135.16, 135.18, 139.97,

140.00, 141.4, 141.8, 141.9, 142.2, 142.3, 142.41, 142.42, 142.6,

142.9, 143.0, 144.49, 144.54, 145.16, 145.23, 145.6, 145.7,

146.0, 146.3, 147.4, 153.2, 157.5, 157.9, 180.3; FT-IR (KBr) ν

(cm^-1) 1656 s (CdO), 1587 s, 1489 m, 1460 m, 1430 m (CdC),

523 s (C₆₀); FAB MS m/ z (rel intensity) 1195 (20, MH⁺), 720

(100, C₆₀⁺); HRMS calcd for C₉₄H₃₄O₂‚H⁺1195.2637, found

1195.2646.

1,4-Dim eth oxyn a p h th a len e 10-Bon d C₆₀Ad d u ct 3b.

Following the general procedure, C₆₀(14.4 mg, 0.02 mmol),

diene 8b (12.1 mg, 0.024 mmol), and toluene (13 mL) were

used. Flash chromatography (toluene/cyclohexane 1:1) gave

the adduct 3b as dark brown crystals (13.9 mg, 59%): ¹H NMR

(360 MHz, CDCl₂-CDCl₂) δ (ppm) 1.02 (s, 6H), 1.53-1.63 (m,

2H), 1.65-1.68 (m, 2H), 1.74 (s, 2H), 1.90-1.98 (m, 2H), 1.98

(s, 2H), 2.08-2.12 (m, 2H), 2.13 (s, 2H), 2.19 (s, 2H), 2.83 (s,

2H), 3.67 (s, 2H), 3.99 (s, 6H), 4.05-4.2 (AB q, J ) 14.1 Hz,

2H), 7.46 (dd, J ) 6.3, 3.3 Hz, 2H), 8.09 (dd, J ) 6.3, 3.3 Hz,

2H); ¹³C NMR (125.8 MHz, CDCl₃/CS₂1:1) δ (ppm) 10.0, 22.7,

29.8, 30.8, 37.8, 38.9, 40.7, 44.1, 44.3, 46.3, 50.8, 54.3, 61.9,

66.6, 121.5, 125.2, 127.7, 135.36, 135.42, 140.03, 140.07, 141.5,

142.05, 142.09, 142.47, 142.54, 142.57, 142.9, 143.1, 144.0,

144.74, 144.76, 145.3, 145.4, 145.64, 145.66, 145.9, 146.2,

146.47, 146.51, 147.7, 158.2, 158.5. No parent ion could be

observed either by FAB or MALDI mass spectroscopy.

Aceta n ilid e 10-Bon d C₆₀Ad d u ct 3d . Following the

general procedure, C₆₀(244 mg, 0.339 mmol), diene 8d (226

mg, 0.5 mmol), and toluene (50 mL) were used. Flash

chromatography with toluene first gave C₆₀(144.6 mg, 59%).

Further elution with toluene/ethyl acetate (3:2) gave the

cycloadduct 3d as dark brown crystals (65.8 mg, 41%): ¹H

NMR (500 MHz, CS₂/acetone-d₆1:1) δ (ppm) 0.98 (s, 3H), 0.99

(s, 3H), 1.54 (br d, J ) 9.3 Hz, 2H), 1.62 (br d, J ) 11.4 Hz,

2H), 1.68 (br d, J ) 8.6 Hz, 2H), 1.79 (m, 3H), 1.94 (br s, 2H),

1.95-1.98 (m, 1H), 1.98 (s, 3H), 2.12 (s, 2H), 2.43 (br s, 2H),

2.90 (br s, 2H), 3.17 (br s, 2H), 4.15-4.3 (AB q, J ) 14.0 Hz,

4H), 6.93 (d, J ) 7.8 Hz, 1H), 7.08 (d, J ) 7.8 Hz, 1H), 7.46 (s,

1H), 8.68 (br s, 1H); ¹³C NMR (125.8 MHz, CS₂/acetone-d₆1:1)

δ (ppm) 10.4, 23.5, 24.3, 31.5, 38.7, 39.8, 44.0, 44.31, 44.32,

44.44, 44.67, 44.82, 47.19, 47.20, 51.6, 51.9, 55.3, 67.2, 113.5,

116.7, 121.1, 136.07, 136.09, 137.8, 140.71, 140.74, 142.17,

142.19, 142.66, 142.72, 142.92, 143.02, 143.14, 143.19, 143.47,

143.49, 143.70, 143.73, 145.33, 145.37, 146.01, 146.04, 146.18,

146.28, 146.44, 146.53, 146.8, 147.1, 148.2, 148.4, 158.5, 159.2,

167.3; FT-IR (KBr) ν (cm^-1) 3421 m br (NsH), 1671 s (CdO),

527 s (C₆₀). No parent ion could be observed either by FAB or

MALDI mass spectroscopy.

Dip yr id op h en a zin e 10-Bon d C₆₀Ad d u ct 3g. Following

the general procedure, C₆₀(36.0 mg, 0.05 mmol), diene 8g (29.8

mg, 0.05 mmol), BHT (5.0 mg, 0.023 mmol), and toluene (18

mL) were used. Flash chromatography (toluene) gave the

product 3g as dark brown crystals (2.8 mg, 4.2%). Compound

3g decomposes during chromatography and on standing in air

and light in solution: ¹H NMR (500 MHz, CDCl₃) δ (ppm) 0.910

(s, 3H), 0.914 (s, 3H), 1.74 (s, 2H), 1.78 (d, J ) 9.3 Hz, 1H),

1.85 (d, J ) 5.8 Hz, 1H), 1.89 (d, J ) 5.8 Hz, 1H), 1.92 (s, 2H),

1.97 (d, J ) 9.3 Hz, 2H), 2.09 (s, 1H), 2.12 (s, 2H), 2.39 (br s,

5H), 2.85 (s, 2H), 3.17 (s, 2H), 4.09 (AB d, J ) 14.1 Hz, 2H),

4.15 (AB d, J ) 14.1 Hz, 2H), 6.25 (s, 1H), 6.65 (dd, J ) 7.7,

2.0 Hz, 1H), 6.90 (d, J ) 1.8 Hz, 1H), 6.99 (d, J ) 7.7 Hz, 1H),

7.21 (br d, J ) 8.3 Hz, 2H), 7.59 (br d, J ) 8.3); ¹³C NMR (125.8

MHz, CDCl₃) δ (ppm) 9.8, 21.6, 22.6, 30.6, 37.7, 38.8, 43.8, 44.1,

46.2, 50.2, 50.3, 54.1, 66.5, 116.2, 119.9, 121.1, 127.3, 129.5,

133.5, 135.4, 136.4, 140.1, 141.5, 142.0, 142.1, 142.40, 142.42,

142.48, 142.6, 142.84, 142.86, 143.08, 143.11, 143.6, 144.73,

144.76, 145.33, 145.35, 145.44, 145.46, 145.53, 145.57, 145.81,

145.86, 145.99, 146.23, 146.27, 146.29, 146.51, 147.7, 149.1,

149.2, 158.1, 158.3; FT-IR (KBr) ν (cm^-1) 1459 m, 1425 m, 1381

m, 1337 m (CdC/CdN), 1155 s, 729 s, 528 s (C₆₀); HRMS calcd

for C₁₀₂H₃₈N₄1318.3096, found 1318.2996.

10-Bon d C₆₀Ad d u ct 3h . Following the general procedure,

C₆₀(14.4 mg, 0.02 mmol), diene 8h (8.7 mg, 0.025 mmol), and

toluene (15 mL) were used. Flash chromatography (cyclohex-

ane/chloroform 9:1) gave the product 3h as dark brown crystals

(18.3 mg, 86%): ¹H NMR (400 MHz, CDCl₂-CDCl₂) δ (ppm)

0.82 (s, 6H), 1.22-1.26 (m, 4H), 1.42-1.65 (m, 6H), 1.75 (s,

2H), 1.94-2.09 (m, 10H), 2.84 (s, 2H), 4.05-4.2 (AB q, J )

14.0 Hz, 4H); ¹³C NMR (100.6 MHz, CDCl₂-CDCl₂) δ (ppm)

10.0, 22.7, 28.8, 30.7, 35.2, 36.2, 37.6, 38.9, 44.1, 45.0, 46.4,

52.7, 54.5, 66.6, 135.44, 135.46, 140.0, 140.1, 141.51, 141.54,

142.06, 142.11, 142.5, 142.55, 142.57, 142.8, 143.1, 144.8,

145.3, 145.38, 145.42, 145.45, 145.6, 145.7, 145.9, 146.0,

146.22, 146.24, 146.49, 146.50, 147.7, 158.1, 158.7; FAB MS

m/ z (rel intensity) 1067 (13, MH⁺), 720 (100, C₆₀⁺); HRMS

calcd for C₈₆H₃₄‚H⁺1067.2739, found 1067.2742.

Du m bbell 14-Bon d Bis-C₆₀Ad d u ct 4. A solution of 26.0

mg (0.058 mmol) of tetraene 9 and 70.0 mg (0.097 mmol) of

C₆₀in 25 mL of oxygen-free o-dichlorobenzene was heated in

the dark under argon at 135 °C for 7.5 h. The crude mixture

was then filtered through a pad of silica gel with cyclohexane.

After evaporation of the solvent in vacuo, the crude solid was

dissolved in a minimum of CS₂. Flash chromatography on

silica gel (a ratio of 100g SiO₂/1 mg material is necessary to

obtain good solubility and separation) with cyclohexane af-

forded two fractions from which the compounds were obtained

by partial evaporation and precipitation from methanol.

Fraction 1 afforded recovered C₆₀(47 mg, 0.065 mmol).

Fraction 2 afforded 25 mg (27%, 81% based on recovered

C₆₀) of compound 4 as a dark brown crystalline material: ¹H

N,N-Dim eth yla n ilin e 10-Bon d C₆₀Ad d u ct 3e. Following

the general procedure, C₆₀(72 mg, 0.1 mmol), diene 8e (43.7

mg, 0.1 mmol), and toluene (30 mL) were used. Flash

chromatography (toluene) gave the product 3e as dark brown

crystals (69.3 mg, 60%): ¹H NMR (500 MHz, CDCl₃) δ (ppm)

0.91 (s, 3H), 0.92 (s, 3H), 1.53 (d, J ) 9.2 Hz, 1H), 1.55 (d, J

) 11.2 Hz, 1H), 1.61 (d, J ) 8.4 Hz, 2H), 1.71 (s, 2H), 1.74 (d,

J ) 9.2 Hz, 1H), 1.92 (s, 4H), 1.95 (d, J ) 8.4 Hz, 2H), 2.05 (d,

J ) 11.2 Hz, 1H), 2.10 (s, 2H), 2.82 (s, 2H), 2.88 (s, 6H), 3.10

(s, 1H), 3.13 (s, 1H), 4.05-4.2 (AB q, J ) 13.9 Hz, 4H), 6.37

(dd, J ) 8.0, 2.3 Hz, 1H), 6.61 (d, J ) 2.3 Hz, 1H), 6.93 (d, J

) 8.0 Hz, 1H); ¹³C NMR (125.8 MHz, CDCl₃) δ (ppm) 9.74,

9.80, 22.6, 30.7, 37.69, 37.72, 39.0, 41.0, 42.7, 43.45, 43.58,

43.94, 44.3, 46.3, 50.9, 51.5, 54.3, 66.2, 106.8, 109.5, 120.8,

5054 J . Org. Chem., Vol. 61, No. 15, 1996

Lawson et al.

NMR (400 MHz, CS₂/CDCl₃5:1) δ (ppm) 0.91 (s, 6H), 1.55 (br

d, J ) 10.4 Hz, 2H), 1.63 (br d, J ) 9.2 Hz, 4H), 1.79 (s, 2H),

1.95 (br s, 8H), 2.04 (br s, 8H), 2.84 (br s, 4H), 4.05-4.2 (AB

q, J ) 14.0 Hz, 8H); ¹³C NMR (500 MHz, o-dichlorobenzene-

d₄/CDCl₃5:1) δ (ppm) 9.8, 22.5, 26.8, 37.5, 38.8, 43.9, 44.7,

46.1, 54.2, 66.3, 119.7, 134.7, 135.2, 139.74, 139.79, 141.14,

141.17, 141.66, 141.70, 142.10, 142.18, 142.55, 142.60, 142.68,

142.86, 144.35, 144.37, 144.98, 145.04, 145.06, 145.15, 145.27,

145.47, 145.52, 145.82, 145.87, 146.13, 146.19, 147.26, 157.7,

158.2; FT-IR (KBr) ν (cm^-1) 1422 m (CdC), 524 s (C₆₀). No

parent ion could be observed by FAB, MALDI, or electrospray²⁹

mass spectroscopy.

Postgraduate Scholarships. The UCLA group thanks

the Dreyfus Foundation for a Camille and Henry

Dreyfus New Faculty Award, the Beckman Foundation

for an Arnold and Mabel Beckman Young Investigator

Award, and the NSF for a Young Investigator Award

(CHE-9457693) to Y.R. A.G.F. acknowledges the Swiss

National Science Foundation for a postdoctoral fellow-

ship. We also thank R. Williams and J . W. Verhoeven

for generously allowing us to report some of their

preliminary photophysical findings on our systems and

Charles L. Wilkins at UC Riverside and Stephen R.

Wilson at New York University for communicating their

preliminary analyses on some of the ball-and-chain

systems.

Ack n ow led gm en t. The UNSW group thanks the

Australian Research Council for support of this work.

A.M.O. acknowledges the award of an Australian Re-

search Fellowship, and D.F.R., M.J .S., and J .M.L. are

grateful for awards of Australian Research Council

J O960512P

Article Doi

Synthesis of a variety of bichromophoric "ball-and-chain" systems based on buckminsterfullerene (C60) for the study of intramolecular electron and energy transfer processes

DOI: 10.1021/jo960512p

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Full text of DOI:10.1021/jo960512p

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