Syntheses of Acetylenic Oligophenylene Macrocycles Based on a Novel Dewar Benzene Building Block Approach

Article abstract of DOI:10.1021/jo0002590

A general synthetic approach to strained p-phenylene-based acetylenic macrocycles is described. A key feature in this approach is exploitation of Dewar benzene as an angular p-phenylene synthon. Thus, 1,4-acetal-bridged 2,5-dichloro(Dewar benzene) 5, prepared in four steps from dimethyl acetylenedicarboxylate and 1,2-dichloroethylene, is applied as such a building block in the syntheses of strained macrocycles 13 and anti-20. For the synthesis of 13, m-phenylene units are used as spacers and modified Eglington-Glaser coupling is applied for the macrocyclization step. For the synthesis of anti-20, on the other hand, o-phenylene units are used as spacers and Sonogashira coupling is applied for the macrocyclization step. Macrocycles 13 and anti-20 are characterized crystallographically, and their strained nature is reflected mainly in the deviation of the acetylene units from linearity; the C≡C-C angles range from 168.7(3)° to 179.9(3)° in 13 and from 168.0(5)° to 171.4(4)° in anti-20. Macrocycle 13 shows unique conformational property, namely, the p-phenylene units arranged in parallel in the rectangular framework rotate freely about the long axes, as evidenced by the ¹H NMR studies. Macrocycle anti-20 exhibits a Stokes shift of 179 nm, which is exceptionally large for phenylacetylene macrocycles, presumably owing to the characteristic stacking structure.

Full text of DOI:10.1021/jo0002590

J . Org. Chem. 2000, 65, 4385-4390
4385
Syn th eses of Acetylen ic Oligop h en ylen e Ma cr ocycles Ba sed on a
Novel Dew a r Ben zen e Bu ild in g Block Ap p r oa ch
Masakazu Ohkita, Kohta Ando, Takanori Suzuki, and Takashi Tsuji*
Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810, J apan
tsuji@science.hokudai.ac.jp
Received February 24, 2000
A general synthetic approach to strained p-phenylene-based acetylenic macrocycles is described. A
key feature in this approach is exploitation of Dewar benzene as an angular p-phenylene synthon.
Thus, 1,4-acetal-bridged 2,5-dichloro(Dewar benzene) 5, prepared in four steps from dimethyl
acetylenedicarboxylate and 1,2-dichloroethylene, is applied as such a building block in the syntheses
of strained macrocycles 13 and anti-20. For the synthesis of 13, m-phenylene units are used as
spacers and modified Eglington-Glaser coupling is applied for the macrocyclization step. For the
synthesis of anti-20, on the other hand, o-phenylene units are used as spacers and Sonogashira
coupling is applied for the macrocyclization step. Macrocycles 13 and anti-20 are characterized
crystallographically, and their strained nature is reflected mainly in the deviation of the acetylene
units from linearity; the CtC-C angles range from 168.7(3)° to 179.9(3)° in 13 and from 168.0(5)°
to 171.4(4)° in anti-20. Macrocycle 13 shows unique conformational property, namely, the
p-phenylene units arranged in parallel in the rectangular framework rotate freely about the long
1
axes, as evidenced by the H NMR studies. Macrocycle anti-20 exhibits a Stokes shift of 179 nm,
which is exceptionally large for phenylacetylene macrocycles, presumably owing to the characteristic
stacking structure.
In tr od u ction
focused on the application of this transformation for more
complex cyclophane systems so far,7 probably because the
oligo(Dewar benzene) precursors are rather laborious to
prepare.
Macrocycles consisting of benzene cores linked by
acetylenic units have attracted considerable recent at-
tention in supramolecular chemistry and materials sci-
ence.1 Owing to the rigid and directional characteristics
of the subunits, they have provided well-defined, shape-
persistent structural motives that show unique associa-
tion behavior2 as well as conformational properties.3 They
have been also regarded as attractive precursors for novel
carbon allotropes and carbon-rich materials.4 Despite the
extensive studies, however, p-phenylene-based, and thus
strained, acetylenic macrocycles are so rare that their
chemistry has not been well developed.5
Valence-bond isomerization of Dewar derivatives is a
useful reaction for generating structurally distorted
benzene derivatives and has been successfully applied
for the preparation of small [n]paracyclophanes.6 Despite
the high potential, however, only little attention has been
We were interested in exploiting a Dewar structure for
the preparation of p-phenylene-based strained macro-
cycles. Since the bent shape of Dewar benzene is expected
to provide a unique template effect on the cyclization,
novel macrocyclic systems that are difficult to access from
planar benzene derivatives may well become available
from the Dewar benzene approach. To investigate these
possibilities, we designed Dewar benzene 5, possessing
a 1,4-acetal bridge that prevents an undesired aromati-
zation of the Dewar form before macrocyclization, as a
building block. In this paper we describe the rational and
efficient syntheses of p-phenylene-based strained mac-
rocycles 13 and anti-20 based on the Dewar benzene
approach using 5.8 Structures and properties of these
novel macrocycles will be also reported.
(1) Hally, M. M.; Pak, J . J .; Brand, S. C. In Topics in Current
Chemistry; de Meijere, A., Ed.; Springer-Verlag: Heidelberg, 2000; Vol.
201, p 81.
(2) (a) Zhang, J .; Pesak, D. J .; Ludwick, J . L.; Moore, J . S. J . Am.
Chem. Soc. 1994, 116, 4227. (b) Shetty, A. S.; Zhang, J .; Moore, J . S.
J . Am. Chem. Soc. 1996, 118, 1019. (c) Tobe, Y.; Utsumi, N.; Kawabata,
K.; Naemura, K. Tetrahedron Lett. 1996, 37, 9325. (d) Tobe, Y.; Utsumi,
N.; Kawabata, K.; Naemura, K. Angew. Chem., Int. Ed. Engl. 1998,
37, 1285.
(3) (a) Bedard, T. C.; Moore, J . S. J . Am. Chem. Soc. 1995, 117,
10662. (b) Ho¨ger, S.; Meckenstock, A.-D.; Muller, S. Chem. Eur. J .
1998, 4, 2423. (c) Romero, M. A.; Fallis, A. G. Tetrahedron Lett. 1994,
35, 4711.
(4) Reviews: (a) Faust, R. Angew. Chem., Int. Ed. Engl. 1998, 37,
2825. (b) Bunz, U. H. F.; Rubin, Y.; Tobe, Y. Chem. Soc. Rev. 1999, 28,
107.
Resu lts a n d Discu ssion
P r ep a r a tion of 5. Dewar benzene 5 was readily pre-
pared in four steps and on a gram scale from dimethyl
(6) Tsuji, T. Advances in Strained and Interesting Organic Molecules;
Halton, B., Ed.; J AI Press: Greenwich, 1999; Vol. 7, p 103 and
references therein.
(7) (a) Tsuji, T.; Ohkita, M.; Nishida, S. J . Am. Chem. Soc. 1993,
115, 5284. (b) Tsuji, T.; Ohkita, M.; Konno, T.; Nishida, S. J . Am. Chem.
Soc. 1997, 119, 8425. (c) Kawai, H.; Suzuki, T.; Ohkita, M.; Tsuji, T.
Angew. Chem., Int. Ed. Engl. 1998, 37, 817. (d) Kawai, H.; Suzuki, T.;
Ohkita, M.; Tsuji, T. Chem. Eur. J ., in press. (e) Wijsman, G. W.; van
Es, D. S.; de Wolf, W. H.; Bickelhaupt, F. Angew. Chem., Int. Ed. Engl.
1993, 32, 726.
(5) (a) Kawase, T.; Darabi, H. R.; Oda, M. Angew. Chem., Int. Ed.
1996, 35, 2664. (b) Haley, M. M.; Langsdorf, B. L. J . Chem. Soc., Chem.
Commun. 1997, 1121. (c) Collins, S. K.; Yap, G. P. A.; Fallis, A. G.
Angew. Chem., Int. Ed. 2000, 39, 385.
(8) Part of the results have been published in preliminary form:
Ohkita, M.; Ando, K.; Yamamoto, K.; Suzuki, T.; Tsuji, T. J . Chem.
Soc., Chem. Commun. 2000, 83.
10.1021/jo0002590 CCC: $19.00 © 2000 American Chemical Society
Published on Web 06/08/2000

4386 J . Org. Chem., Vol. 65, No. 14, 2000
Ohkita et al.
Sch em e 1a
isomerization of 12 proceeded smoothly by irradiation
with a high-pressure mercury lamp through Pyrex at 12
°C to afford 13 in quantitative yield. The clean and
quantitative conversion of 12 into 13 was further sup-
ported by the UV monitoring of the reaction, which
showed an isosbestic point at 295 nm. The less sym-
metrical product resulting from the rearrangement of
only one of the Dewar benzene units was not detected in
1
the H NMR monitoring of the reaction.
1
It is interesting to note that, in the H NMR spectra,
the benzylic methylene protons of 13 appear as a singlet
(δ 4.95) whereas those of 12 appear as a pair of AB
doublets (δ 4.10 and 4.12, J ) 11.0 Hz), indicating that
these protons are diastereotopic in 12 and operationally
enantiotopic in 13. These observations would be most
reasonably explained by postulating fast interconversion
of 13a with the rotamer 13b, namely, fast rotation of the
p-phenylene unit(s) in 13 on the NMR time scale (Scheme
3). Molecular modeling shows, in fact, that such rotation
requires no serious deformation of the macrocyclic frame-
work.13 Further elaboration of 13 would provide an
interesting structural motif with unique conformational
properties; for example, transmission-type combined
rotation could be achieved if the residues R in 13 interact
sterically with each other.
X-r a y Cr ysta llogr a p h ic Stu d y on 13. Crystals of 13
suitable for X-ray structure determination (see Support-
ing Information) were obtained by slow diffusion of
ethanol into a solution of 13 in chloroform at room
temperature. The molecule adopts a nearly planar con-
formation in the crystal, and the dimension of the
framework is 7.32 Å × 11.54 Å, as defined by the four
inner m-phenylene carbon atoms. Interestingly, the
framework appears to be distorted to a parallelogram to
accommodate two SiMe2OCH2 moieties inside the cavity.
The twist angles of the benzene rings from the least-
square plane formed by the acetylenic carbon atoms are
3.7° and 0.4° in the m-phenylene units and 3.4° in the
p-phenylene units. The benzene rings are essentially
planar (deviation < 0.01 Å), while the acetylene units
show deviation from linearity with the CtC-C angles
ranging from 168.7(3)° to 179.9(3)°.
Syn th esis of a n ti-20. To explore the scope of the
present Dewar benzene building block approach, the
synthesis of anti-20 was next carried out as outlined in
Scheme 4. In the synthesis, o-phenylene units were used
as spacers and Sonogashira coupling14 was applied for
the crucial macrocyclization step. Macrocycle anti-20
would also be regarded as a novel example of alkynyl-
based fully unsaturated paracyclophanes.15 Singly pro-
tected 1,2-diethynylbenzene 16 was prepared in 63%
yield by the successive coupling of 1-bromo-2-iodobenzene
(14) with (trimethylsilyl)acetylene and 2-methyl-3-butyn-
2-ol followed by desilylation of the diethynylation product
15 with Bu4NF. Palladium-catalyzed coupling of 5 with
16 gave monoethynylated product 17 in 57% yield.
a
(a) hν, 1,2-dichloroethylene, -70 °C, 12 h, 27%; (b) LiAlH4,
Et2O, 89%; (c) 1,1-dimethoxycyclohexane, TsOH, benzene, 68%;
(d) t-BuOK, THF, 45% of 5 and 35% of 6.
acetylenedicarboxylate(1)and 1,2-dichloroethylene(Scheme
1).9 Thus, irradiation of 1 in a 1:1 mixture of 1,2-
dichloroethylene and dichloromethane with a high-pres-
sure mercury lamp afforded bicyclo[2.2.0]hexane deriva-
tives 2 in 27% yield as a mixture of five stereoisomers
with regard to the chlorine substituents. LiAlH4 reduc-
tion of the esters 2 followed by treatment of the resulting
diols 3 with 1,1-dimethoxycyclohexane under the influ-
ence of a catalytic amount of TsOH provided 4 in 61%
yield. Cyclohexylidene was an acetal of choice because
of its adequate stability toward acid hydrolysis. Dehy-
drochlorination of 4 with t-BuOK in THF at room
temperature afforded desired 5 (45%) together with its
regioisomer 6 (35%), which were separated by conven-
tional column chromatography. Differentiation between
5 and 6 was readily made by examining their 1H NMR
spectra; acetal methylene protons in 5 appear as a pair
of AB doublets (δ 3.95 and 3.98, J ) 13.2 Hz), whereas
those in 6 appear as two singlets (δ 3.98 and 4.00).
Furthermore, the structure of crystalline 5 was unam-
biguously determined by X-ray crystallography. The
structural analysis also revealed that a dihedral angle
of the Dewar benzene is 116°. We thus evaluated that
an angle of about 120°, similar to a m-phenylene unit,
may be applicable for the macrocyclization using 5.
Syn th esis of 13. The synthesis of 13 was carried out
as outlined in Scheme 2. In the synthesis, m-phenylene
units were used as spacers and modified Eglington-
Glaser coupling10 was applied for the crucial macrocy-
clization step. Singly protected 1,3-diethynylbenzene 8
was prepared in 43% yield by partial desilylation of 1,3-
bis[(trimethylsilyl)ethynyl]benzene (7)11 with aqueous
KOH in MeOH followed by purification by distillation.
Palladium-catalyzed coupling of 5 with 8 afforded di-
ethynylation product 9 in 55% yield, which was then
deprotected to the terminal acetylene 10 in 76% yield.
Copper-mediated oxidative coupling of 10 with CuCl/Cu-
10
(OAc)2 in pyridine under pseudo-high-dilution condi-
tions produced cyclic dimer 11 in 70% yield.12 Acid
hydrolysis of the acetal 11 followed by silylation of the
resulting tetraol afforded 12 in 68% yield. Photochemical
(12) The isolated 11 was spectroscopically homogeneous although
two stereoisomers arising from relative orientation of the Dewar units
are possible. Compound 12 was also spectroscopically homogeneous.
(13) Similar rotation of spindles in phenylacetylene macrocycles, see
ref 3.
(14) Sonogashira, K.; Tohda, Y.; Hagihara, N. Tetrahedron Lett.
1975, 4467.
(15) Examples of alkynyl-based paracyclophanes, see (a) Hopf, H.;
J ones, P. G.; Bubenitschek, P.; Werner, C. Angew. Chem., Int. Ed. Engl.
1995, 34, 2367. (b) Bauer, M.; Nieger, M.; Vo¨gtle, F. Chem. Ber. 1992,
125, 2533.
(9) Tsuji, T.; Watanabe, H.; Tanaka, J .; Inada, M.; Nishida, S. Chem.
Lett. 1990, 1193.
(10) (a) O’Krongly, D.; Denmade, S. R.; Chiang, M. Y.; Breslow, R.
J . Am. Chem. Soc. 1985, 107, 5544. (b) De Meijere, A.; Kozhushkov,
S.; Haumann, T.; Boese, R.; Puls, C.; Cooney, M. J .; Scott, L. T. Chem.
Eur. J . 1995, 1, 124.
(11) Neenan, T. X.; Whitesides, G. M. J . Org. Chem. 1988, 53, 2489.

Syntheses of Acetylenic Oligophenylene Macrocycles
J . Org. Chem., Vol. 65, No. 14, 2000 4387
Sch em e 2a
Sch em e 4a
a
(a) 1 N KOH, MeOH, 30 min, 43%; (b) 5, Pd(PPh3)4, CuI, Et3N,
55%; (c) Bu4NF, THF, 76%; (d) Cu(OAc)2, CuCl, Py, 60 °C, syringe-
pump (over 2 h), 70%; (e) (i) 1 N HCl, THF, (ii) t-BuMe2SiOTf,
Et3N, 68%; (f) hν, CH2Cl2, 12 °C, 100%.
a
(a) (i) (trimethylsilyl)acetylene, Pd(PPh3)4, CuI, Et3N, 95%, (ii)
2-methyl-3-butyne-2-ol, Pd(PPh3)4, CuI, Et3N, 72%; (b) Bu4NF,
THF, 92%; (c) 5, Pd(PPh3)4, CuI, Et3N, 57%; (d) tricaprylylmethy-
lammonium chloride, 5 N NaOH, benzene, Pd(PPh3)4, CuI, 80 °C,
22%; (e) (i) 1 N HCl, THF, (ii) i-Pr3SiOTf, Et3N, 72%; (f) hν, CH2Cl2,
12 °C, 74%.
Sch em e 3
determination (see Supporting Information) were grown
by vapor diffusion of methanol into a chloroform solution
of anti-20 at room temperature. The p-phenylene units
are almost parallel with the interplanar distance of 3.48
Å, and the angles between the macrocyclic plane and the
p-phenylene benzene rings are 62.5° and 64.2°. The
acetylene units show deviation from linearity with the
CtC-C angles ranging from 168.0(5)° to 171.4(4)°. The
transannular distances between the acetylenic carbon
atoms are 2.75 and 2.76 Å.
Electronic absorption and emission spectra of anti-20
are shown in Figure 1. It is interesting to note that anti-
20 exhibits a large Stokes shift (179 nm), which is not
commonly observed for phenylacetylene macrocycles19 or
linear p-phenylene ethynylenes.20 Since the suitable
overlap of the p-phenylene units is found for anti-20 in
the X-ray structure, the observed long-wavelength fluo-
rescence might be attributable to the intramolecular
excimer-like emission resulting from the stacking struc-
ture.
Cyclodimerization of 17 to 18 was achieved by an in situ
deprotection/alkynylation sequence under phase-transfer
conditions.16 We found that tricaprylylmethylammonium
choride was a superior catalyst to conventional benzyl-
triethylammonium choride16 for this reaction; the latter
gave only a trace amount of 18, whereas the former
afforded 18 in 22% yield as an inseparable mixture of
meso- and dl-isomers (4:6). Acid hydrolysis of 18 followed
by silylation of the resulting tetraols afforded 19 in 72%
yield, which was then separated into the meso- and dl-
isomers by preparative HPLC. Photochemical isomeriza-
tion of dl-19 by irradiation with a high-pressure mercury
lamp through Pyrex in CH2Cl2 at 12 °C afforded anti-20
in 74% yield. Unexpectedly, meso-19 decomposed under
the same photolysis conditions and produced no identifi-
able product; the reason is not clear at the present.17
X-r a y Str u ctu r e a n d Sp ectr oscop ic P r op er ties of
a n ti-20. Crystals of anti-20 suitable for X-ray structure
(17) The isomerization of 19 into 20 must result in shortening of
the distance between the acetylenic groups, which has been proposed
as the crucial geometrical change triggering the Bergman cyclization
of some enediyne antitumor antibiotics (ref 18), so that the possible
Bergman cyclizations of 19 as well as 20 in 1,4-cyclohexadiene were
examined. However, no information about the intermediacy of the
cycloaromatization products was obtained under thermal or photo-
chemical reaction conditions.
(18) Reviews: (a) Bergman, R. G. Acc. Chem. Res. 1973, 6, 25. (b)
Nicolaou, K. C.; Dai, W.-M. Angew. Chem., Int. Ed. Engl. 1991, 30,
1387.
(16) (a) Huynh, C.; Linstrumelle, G. Tetrahedron 1988, 44, 6337.
(b) Tobe, Y.; Matsumoto, H.; Naemura, K.; Achiba, Y.; Wakabayashi,
T. Angew. Chem., Int. Ed. 1996, 35, 1800. (c) Nishinaga, T.; Kawamura,
T.; Komatsu, K. J . Org. Chem. 1997, 62, 5354.
(19) Exceptionaly large Stokes shift (121 nm) has been reported for
cyclic [6]paraphenylacetylene (ref 5a).
(20) Davey, A. P.; Elliott, S.; O’Connor, O.; Blau, W. J . Chem. Soc.,
Chem. Commun. 1995, 1433.

4388 J . Org. Chem., Vol. 65, No. 14, 2000
Ohkita et al.
vigorous stirring. The precipitate was filtered off, and the
ethereal solution was dried with Na2SO4. Evaporation of the
solvent gave crude alcohol 3 (8.78 g, 89%), which was used for
the next step without purification. IR (neat) 3324, 1044 cm-1
.
A mixture of 3 (8.78 g, 31.4 mmol), 1,1-dimethoxycyclohex-
ane (9.46 g, 65.6 mmol), and TsOH (0.60 g, 3.1 mmol) in
benzene (280 mL) was heated to reflux, and MeOH generated
was azeotopically distilled off through Vigreux column (30 cm).
After 3 h, the mixture was cooled to room temperature, washed
successively with 5% aqueous NaHCO3 (150 mL) and brine
(150 mL), dried with Na2CO3/Na2SO4 (1:1), concentrated, and
chromatographed on silica gel eluted with ether/hexane (2:
98) to afford 4.77 g (68%) of stereoisomeric acetals 4. IR (KBr)
2936, 2856, 1448, 1100, 1044 cm-1
.
To a stirred solution of 4 (8.88 g, 24.7 mmol) in dry THF
(160 mL) was added a solution of t-BuOK (13.87 g, 123.8 mmol)
in dry THF (200 mL) over 40 min at 0 °C under argon. The
mixture was stirred at room temperature for 2.5 h, evaporated
to remove THF, diluted with ether (600 mL), washed succes-
sively with water (300 mL) and brine (300 mL), dried with
Na2SO4, concentrated, and chromatographed on silica gel
eluted with ether/hexane (3:97) to give 3.20 g (45%) of 5 as
crystals and 2.45 g (35%) of 6 as an oil. 5: mp 93.5-94 °C
F igu r e 1. Electronic absorption (line) and fluorescence emis-
sion (dotted line) spectra of anti-20 in dichloromethane (5 ×
10-6 M); λmax 290 nm, λem 469 nm.
Con clu sion
In conclusion, we have successfully synthesized and
characterized novel p-phenylene-based strained macro-
cycles 13 and anti-20 through a macrocyclization-
deprotection-aromatization sequence by using Dewar
benzene 5 as a building block. The present results
demonstrate that a Dewar benzene unit can be exploited
as a masked p-phenylene unit for the construction of
strained macrocyclic systems. By using other spacers and/
or connection modes, a variety of p-phenylene-containing
strained macrocycles with unique structures and proper-
ties may well become available on the basis of the present
building block approach.
1
(hexane); H NMR (90 MHz, CDCl3) δ 1.40-1.73 (m, 10 H),
3.95 (d, J ) 13.2 Hz, 2 H), 3.98 (d, J ) 13.2 Hz, 2 H), 6.31 (s,
2 H); 13C NMR (100 MHz, CDCl3) δ 22.72, 25.64, 33.07, 57.44,
64.50, 103.80, 133.08, 140.56; IR (KBr) 1564, 1098 cm-1; MS
(FD) m/z 290 (M+ + 4, 13), 286 (M+ + 2, 65), 286 (M+, 100).
Anal. Calcd for C14H16O2Cl2: C, 58.55; H, 5.62; Cl, 24.69.
Found: C, 58.28; H, 5.72; Cl, 24.74. 6: 1H NMR (90 MHz,
CDCl3) δ 1.40-1.73 (m, 10 H), 3.98 (s, 2 H), 4.00 (s, 2 H), 6.28
(s, 2 H); 13C NMR (100 MHz, CDCl3) δ 22.75, 25.66, 32.92,
55.69, 57.88, 59.57, 70.25, 103.80, 134.45, 139.59; IR (neat)
1580, 1104 cm-1; MS (FD) m/z 290 (M+ + 4, 17), 286 (M+ + 2,
71), 286 (M+, 100). Anal. Calcd for C14H16O2Cl2: C, 58.55; H,
5.62; Cl, 24.69. Found: C, 58.21; H, 5.79; Cl, 24.75.
Exp er im en ta l Section
1-(Tr im eth ylsilyl)eth yn yl-3-eth yn ylben zen e (8). To a
degassed solution of 711 (2.7 g, 10 mmol) in MeOH (100 mL)
was added 1 N aqueous KOH (0.03 mL), and the mixture was
stirred at room temperature under argon. After 30 min, the
mixture was poured into pentane (300 mL), washed succes-
sively with water (300 mL) and brine (100 mL), dried with
Na2SO4, concentrated, and distilled to give 0.85 g (43%) of 8
as a colorless liquid, whose purity was >95% by GLC analysis
(10% Silicon SE-30, 0.5 m, 80-180 °C). 8: bp 55-60 °C (10-3
Torr); 1H NMR (90 MHz, CDCl3) δ 0.24 (s, 9 H), 3.06 (s, 1 H),
7.20-7.50 (m, 4 H); 13C NMR (100 MHz, CDCl3) δ -0.11, 77.73,
82.79, 95.15, 103.91, 122.37, 123.52, 128.31, 132.00, 132.15,
135.52; IR (neat) 3304, 2152 cm-1; MS (EI) m/z 198 (M+, 24),
183 (M+ - 15, 100); HRMS calcd for C13H14Si 198.0864, found
198.0877.
P a lla d iu m -Ca ta lyzed Cou p lin g of 5 w ith 8. To a de-
gassed suspension of 5 (360 mg, 1.25 mmol), Pd(PPh3)4 (70 mg,
0.06 mmol), and CuI (12 mg, 0.06 mmol) in dry triethylamine
(40 mL) was added a degassed solution of 8 (600 mg, 3.0 mmol)
in degassed triethylamine (5 mL). The mixture was stirred at
70 °C under argon for 12 h, cooled, evaporated to remove
triethylamine, taken up in ether (200 mL), and washed with
1 N aqueous HCl (3 × 100 mL). The aqueous solution was
extracted with ether (2 × 100 mL). The organic extracts were
combined, washed successively with aqueous NaHCO3 (200
mL) and brine (200 mL), dried with Na2SO4, concentrated, and
chromatographed on silica gel eluted with ether/hexane (2:
98) to give 421 mg (55%) of 9 as colorless amorphous: 1H NMR
(400 MHz, CDCl3) δ 1.41-1.75 (m, 10 H), 0.25 (s, 18 H), 4.07
(d, J ) 13.2 Hz, 2 H), 4.13 (d, J ) 13.2 Hz, 2 H), 6.79 (s, 2 H),
7.25 (t, J ) 7.8 Hz, 2 H), 7.38 (dt, J ) 7.8, 1.5 Hz, 2 H), 7.40
(dt, J ) 7.8, 1.5 Hz, 2 H), 7.57 (t, J ) 1.5 Hz, 2 H); 13C NMR
(100 MHz, CDCl3) δ -0.09, 22.81, 25.73, 33.30, 58.71, 64.52,
83.54, 95.12, 103.18, 103.64, 103.97, 122.97, 123.12, 128.33,
131.47, 131.93, 135.04, 135.06, 144.28; IR (neat) 2156, 1598,
1476, 1250 cm-1; MS (FD) m/z 610 (M+, 100).
Gen er a l. 1,3-Bis[(trimethylsilyl)ethynyl]benzene (7)11 was
prepared following the known procedure. Other reagents and
solvents were obtained from commercial sources and purified
prior to use.
1,3-Bis(m et h oxyca r b on yl)-2,3,5,6-t et r a ch lor ob icyclo-
[2.2.0]h exa n es (2). A solution of 1 (8.0 g, 56.3 mmol) in a 1:1
mixture of 1,2-dichloroethylene (a mixture of cis and trans
isomers) and dichloromethane (220 mL) was distributed in
eight quartz tubes (18 mm × 23 cm), bubbled with argon for
10 min, and irradiated with a high-pressure Hg lamp at -70
°C. The reaction was monitored by GLC (10% Silicon SE-30,
0.5 m, 100-270 °C), and the irradiation was terminated after
12 h (35% GLC conversion). The combined reaction mixture
was concentrated to recover the unreacted 1,2-dichloroethylene
and 1. The distillation of the residue in vacuo gave 5.20 g (27%)
of 2, from which five stereoisomers were isolated by prepara-
tive GLC (5% Silicon XE-60, 2 m, 100-200 °C). 2a : mp 74-
74.5 °C; 1H NMR (90 MHz, CDCl3) δ 3.83 (s, 6 H), 4.75 (d, J )
7.6 Hz, 2 H), 4.97 (d, J ) 7.6 Hz, 2 H). 2b: mp 112-112.5 °C;
1H NMR (90 MHz, CDCl3) δ 3.80 (s, 3 H), 3.91 (s, 3 H), 4.70
(d, J ) 5.8 Hz, 2 H), 5.32 (d, J ) 5.8 Hz, 2 H). 2c: mp 110-
110.5 °C; 1H NMR (90 MHz, C6D6) δ 3.13 (s, 6 H), 4.68 (d, J )
9.1 Hz, 1 H), 4.71 (d, J ) 9.1 Hz, 1 H), 5.41 (s, 2 H). 2d : mp
88-89.5 °C; 1H NMR (90 MHz, CDCl3) δ 3.81 (s, 3 H), 3.85 (s,
3 H), 4.46 (d, J ) 7.3 Hz, 1 H), 4.81 (d, J ) 5.9 Hz, 1 H), 4.89
(d, J ) 7.3 Hz, 1 H), 5.26 (d, J ) 5.9 Hz, 1 H). 2e: mp 85-
1
85.5 °C; H NMR (90 MHz, CDCl3) δ 3.82 (s, 6 H), 5.10 (s, 2
H), 5.24 (s, 2 H); IR (KBr) 1746, 1440, 1334, 1264, 1220 cm-1
.
Anal. Calcd for C10H10O4Cl4: C, 35.75; H, 3.00; Cl, 42.21.
Found: C, 35.77; H, 2.90; Cl, 42.22.
Spir o[cycloh exan e-1,4′-3′,5′-dioxa-8′,10′-dich lor obicyclo-
[2.2.0]h exa -8′,10′-d ien e] (5). To a suspension of lithium
aluminum hydride (2.68 g, 70.7 mmol) in dry ether (420 mL)
was added dropwise a solution of 2 (11.88 g, 35.4 mmol, a
mixture of stereoisomers) in dry ether (220 mL) over 90 min
under argon. After the addition, the mixture was refluxed for
2 h, cooled, and treated successively with water (2.7 mL), 15%
aqueous sodium hydroxide (2.7 mL), and water (8.1 mL) with
Desilyla tion of 9. To a degassed suspension of 9 (400 mg,
0.66 mmol) in THF (10 mL) was added Bu4NF (2 mL, 1 M
solution in THF, 2.0 mmol) dropwise, and the reaction was

Syntheses of Acetylenic Oligophenylene Macrocycles
J . Org. Chem., Vol. 65, No. 14, 2000 4389
stirred at room temperature for 30 min. The mixture was
evaporated to remove THF, taken up in ether (150 mL),
washed successively with water (50 mL) and brine (50 mL),
dried with Na2SO4, concentrated, and chromatographed on
silica gel eluted with ether/hexane (5:95) to give 233 mg (76%)
of colorless amorphous 10: 1H NMR (400 MHz, CDCl3) δ 1.4-
1.8 (m, 10 H), 3.08 (s, 2 H), 4.07 (d, J ) 13.2 Hz, 2 H), 4.13 (d,
J ) 13.2 Hz, 2 H), 6.81 (s, 2 H), 7.28 (t, J ) 7.8 Hz, 2 H), 7.42
(dt, J ) 7.8, 1.5 Hz, 2 H), 7.43 (dt, J ) 7.8, 1.5 Hz, 2 H), 7.58
(t, J ) 1.5 Hz, 2 H); 13C NMR (100 MHz, CDCl3) δ 22.81, 25.73,
33.23, 58.71, 64.59, 77.91, 82.63, 83.67, 95.39, 103.68, 122.53,
123.12, 128.46, 131.86, 132.17, 135.13, 139.58, 144.53; IR
(neat) 3300, 2936, 1600, 1476, 1096, 758 cm-1; MS (FD) m/z
466 (M+, 100).
Cyclod im er iza tion of 10. To a degassed slurry of CuCl
(930 mg, 9.4 mmol) and Cu(OAc)2 (2.3 g, 12.5 mmol) in dry
pyridine (300 mL) was added dropwise a degassed solution of
10 (146 mg, 0.31 mmol) in dry pyridine (30 mL) over 2 h at 60
°C. The mixture was stirred for an additional 1 h at the same
temperature, cooled, evaporated to remove pyridine, taken up
in EtOAc (200 mL), and washed with ice-cooled 1 N aqueous
HCl (200 mL). The aqueous solution was extracted with EtOAc
(3 × 100 mL). The organic extracts were combined, washed
successively with aqueous NaHCO3 (200 mL) and brine (200
mL), dried with Na2SO4, concentrated, and chromatographed
on silica gel eluted with chloroform to give 102 mg (70%) of
colorless amorphous 11: 1H NMR (400 MHz, CDCl3) δ 1.4-
1.8 (m, 20 H), 4.08 (d, J ) 13.2 Hz, 4 H), 4.15 (d, J ) 13.2 Hz,
4 H), 6.86 (s, 4 H), 7.31 (t, J ) 7.8 Hz, 4 H), 7.42 (dt, J ) 7.8,
1.5 Hz, 4 H), 7.43 (dt, J ) 7.8, 1.5 Hz, 4 H), 7.71 (t, J ) 1.5
Hz, 4 H); 13C NMR (100 MHz, CDCl3) 22.84, 25.73, 33.50,
58.76, 65.00, 74.54, 80.98, 84.05, 95.04, 103.71, 122.15, 123.35,
128.64, 131.42, 131.55, 136.98, 136.99, 145.26; IR (neat) 1596,
1474, 1156, 1098 cm-1; MS (FD) m/z 929 (M+ + 1, 100), 928
(M+, 100).
Bis(Dew a r ben zen e) P r ecu r sor 12. To a solution of 11
(102 mg, 0.11 mmol) in THF (40 mL) was added 1 N aqueous
HCl (4 mL), and the reaction was stirred at room temperature
for 14 h. The mixture was evaporated to remove THF, treated
with saturated aqueous NaHCO3 (50 mL), and extracted with
EtOAc (3 × 50 mL). The organic extracts were combined,
washed with brine (50 mL), dried with Na2SO4, and concen-
trated to give a solid (126 mg), which was dissolved in dry
dichloromethane (50 mL). To the dichloromethane solution was
added successively triethylamine (167 mg, 1.65 mmol) and
t-BuMe2SiOTf (175 mg, 0.66 mmol), and the mixture was
stirred at room temperature under argon for 6 h. The mixture
was diluted with 1 N aqueous HCl (50 mL) and extracted with
dichloromethane (2 × 50 mL). The extracts were combined,
washed successively with saturated aqueous NaHCO3 (30 mL)
and brine (30 mL), dried with Na2SO4, concentrated, and
purified by preparative GPC (J AIGEL-1H, 2 × 20 mm φ ×
600 mm, chloroform) to give 92 mg (68%, two steps) of colorless
amorphous 12: 1H NMR (400 MHz, CD2Cl2) δ 0.08 (s, 24 H),
0.92 (s, 36 H), 4.10 (d, J ) 11.0 Hz, 4 H), 4.12 (d, J ) 11.0 Hz,
4 H), 6.83 (s, 4 H), 7.29 (t, J ) 7.8 Hz, 4 H), 7.38 (dt, J ) 7.8,
1.5 Hz, 4 H), 7.52 (dt, J ) 7.8, 1.5 Hz, 4 H), 7.70 (t, J ) 1.5
Hz, 4 H); 13C NMR (100 MHz, CD2Cl2) δ -5.36, -5.23, 18.61,
26.05, 60.93, 66.42, 74.62, 81.31, 85.05, 94.77, 122.42, 124.11,
129.12, 131.75, 131.85, 136.18, 137.14, 146.02; IR (KBr) 1258,
1104, 838 cm-1; MS (FD) m/z 1224 (M+, 100).
1104, 838 cm-1; UV (CH2Cl2) λmax (log ꢀ) ) 262.5 (4.68), 277.5
(4.51), 293.5 (4.63), 312 (4.72), 334 (4.60), 354 nm (3.44);
fluorescence (CH2Cl2, λex ) 313 nm) λem ) 365, 383 nm; MS
(FD) m/z 1225 (M+ + 1, 100), 1224 (M+, 94); HRMS calcd for
C80H88O4Si4 1224.5800, found 1224.5780.
1-[(1-Meth yl-1-h yd r oxyeth yl)eth yn yl]-3-[(tr im eth ylsi-
lyl)eth yn yl]ben zen e (15). To a degassed suspension of 14
(5.62 g, 19.9 mmol), Pd(PPh3)4 (460 mg, 0.40 mmol), and CuI
(37 mg, 0.19 mmol) in dry triethylamine (200 mL) was added
(trimethylsilyl)acetylene (2.14 g, 21.9 mmol), and the mixture
was stirred at 70 °C under argon. After 2 days, the mixture
was cooled, evaporated to remove triethylamine, diluted with
water (200 mL), and extracted with ether (2 × 200 mL). The
extracts were combined, washed with brine (200 mL), dried
with Na2SO4, concentrated, and chromatographed on silica gel
eluted with hexane to give an oil (4.43 g, 95%), which was
dissolved in dry triethylamine (90 mL). To the degassed
solution was added Pd(PPh3)4 (204 mg, 0.18 mmol), CuI (17
mg, 0.09 mmol), and 2-methyl-3-butyne-2-ol (1.49 g, 17.7
mmol), and the mixture was stirred at 65 °C under argon. After
5 days, the mixture was cooled, evaporated to remove triethyl-
amine, diluted with water (200 mL), and extracted with EtOAc
(2 × 200 mL). The extracts were combined, washed with brine
(200 mL), dried with Na2SO4, concentrated, and chromato-
graphed on silica gel eluted with ether/hexane (2:8) to give 15
(1.63 g, 72%) as an oil: 1H NMR (90 MHz, CDCl3) δ 0.27 (s, 9
H), 1.64 (s, 6 H), 7.17-7.52 (m, 4 H); 13C NMR (100 MHz,
CDCl3) δ 0.05, 31.52, 65.71, 80.90, 97.79, 98.20, 103.31, 125.33,
125.63, 127.89, 128.15, 131.82, 132.37; IR (neat) 3356, 2156,
1164 cm-1; MS (FD) m/z 256 (M+, 100); HRMS calcd for C16H20
-
OSi 256.1283, found 256.1297.
1-[(1-Met h yl-1-h yd r oxyet h yl)et h yn yl]-3-et h yn ylb en -
zen e (16). To a degassed solution of 15 (1.61 g, 6.3 mmol) in
THF (400 mL) was added Bu4NF (1 M solution in THF, 12.6
mL, 12.6 mmol), and the reaction was stirred at 0 °C under
argon. After 3 h, the mixture was evaporated to remove THF,
diluted with water (100 mL), and extracted with ether (2 ×
150 mL). The extracts were combined, washed with brine (100
mL), dried with Na2SO4, concentrated, and chromatographed
on silica gel eluted with ether/hexane (2:8) to give 16 (1.07 g,
92%) as an oil: 1H NMR (90 MHz, CDCl3) δ 1.64 (s, 6 H), 3.28
(s, 1 H), 7.21-7.55 (m, 4 H); 13C NMR (100 MHz, CDCl3) δ
31.40, 65.70, 80.63, 80.71, 82.11, 98.07, 124.78, 125.76, 127.95,
128.47, 131.72, 132.46; IR (neat) 3292, 1164 cm-1; MS (FD)
m/z 184 (M+, 100); HRMS calcd for C13H12O 184.0888, found
184.0895.
P a lla d iu m -Ca ta lyzed Cou p lin g of 5 w ith 16. To a
degassed suspension of 5 (1.45 g, 5.0 mmol), Pd(PPh3)4 (117
mg, 0.10 mmol), and CuI (19 mg, 0.10 mmol) in dry triethyl-
amine (80 mL) was added a degassed suspension of 16 (0.93
g, 5.0 mmol) in dry triethylamine (20 mL), and the mixture
was stirred at 65 °C under argon. After 19 h, the mixture was
cooled, evaporated to remove triethylamine, diluted with water
(100 mL), and extracted with ether (2 × 100 mL). The extracts
were combined, washed with brine (100 mL), dried with Na2-
SO4, concentrated, and chromatographed on silica gel eluted
with ether/hexane (2:8) to give 17 (1.25 g, 57%) as an oil: 1H
NMR (300 MHz, CDCl3) δ 1.40-1.71 (m, 10 H), 3.96 (d, J )
13.2 Hz, 1 H), 4.04 (d, J ) 13.2 Hz, 1 H), 4.06 (d, J ) 13.2 Hz,
1 H), 4.17 (d, J ) 13.2 Hz, 1 H), 6.37 (s, 1 H), 6.71 (s, 1 H),
7.25-7.44 (m, 4 H); 13C NMR (100 MHz, CDCl3) δ 25.02, 27.03,
31.36, 31.52, 42.00, 58.06, 58.58, 64.74, 65.61, 67.80, 77.23,
80.58, 85.83, 95.90, 98.55, 124.99, 125.46, 127.99, 128.56,
131.74, 13176, 134.20, 135.06, 139.95, 141.93; IR (neat) 3432
cm-1; MS (FD) m/z 434 (M+, 100).
Ma cr ocycle 13. A solution of 12 (11.0 mg, 0.009 mmol) in
dichloromethane (25 mL) was placed in a Pyrex test tube (18
mm × 18 cm), bubbled with argon for 15 min at 0 °C, and
irradiated with a high-pressure Hg lamp at 12 °C. The reaction
was monitored by HPLC, which showed the formation of a
single product. After 30 min (100% conversion), the irradiation
was terminated, and the mixture was evaporated to give 11.0
Cyclod im er iza tion of 17. To a degassed suspension of 17
(254 mg, 0.59 mmol), tricaprylylmethylammonium chloride (73
mg, 0.18 mmol), Pd(PPh3)4 (14 mg, 0.012 mmol), PPh3 (3 mg,
0.011 mmol), and CuI (1 mg, 0.005 mmol) in benzene (12 mL)
was added 5 N aqueous NaOH (4.5 mL), and the mixture was
stirred at 80 °C under argon. After 38 h, the mixture was
cooled, treated with 1 N aqueous HCl (25 mL), and extracted
with benzene (3 × 30 mL). The extracts were combined,
washed with brine (30 mL), dried with Na2SO4, concentrated,
and chromatographed on silica gel eluted with EtOAc/benzene
1
mg (100%) of 13 as colorless powder: mp >280 °C; H NMR
(400 MHz, CD2Cl2) δ 0.15 (S, 24 H), 0.96 (s, 36 H), 4.95 (s, 8
H), 7.36 (t, J ) 7.8 Hz, 4 H), 7.41 (dt, J ) 7.8, 1.5 Hz, 4 H),
7.49 (dt, J ) 7.8, 1.5 Hz, 4 H), 7.66 (s, 4 H), 7.88 (t, J ) 1.5
Hz, 4 H); 13C NMR (100 MHz, CD2Cl2) δ -5.07, 18.82, 26.24,
63.56, 75.37, 82.73, 89.08, 95.11, 120.79, 122.62, 124.36,
129.32, 130.13, 130.34, 130.92, 139.73, 142.36; IR (KBr) 1258,

4390 J . Org. Chem., Vol. 65, No. 14, 2000
Ohkita et al.
(2:98) to give colorless amorphous 18 (43 mg, 22%, a 60:40
mixture of stereoisomers): 1H NMR (400 MHz, CDCl3) δ 1.40-
1.71 (m, 20 H), 4.07 (d, J ) 13.2 Hz, 4 H of the meso-isomer),
4.08 (d, J ) 13.2 Hz, 4 H of the dl-isomer), 4.14 (d, J ) 13.2
Hz, 4 H of the meso-isomer), 4.15 (d, J ) 13.2 Hz, 4 H of the
dl-isomer), 6.80 (s, 4 H of the dl-isomer), 6.81 (s, 4 H of the
meso-isomer), 7.27-7.30 (m, 4 H), 7.42-7.46 (m, 4 H); IR (KBr)
2936, 2860, 1100 cm-1; MS (FD) m/z 680 (M+, 83), 99 (100).
Bis(Dew a r ben zen e) P r ecu r sor s 19. To a solution of 18
(37 mg, 0.054 mmol) in THF (5 mL) was added 1 N aqueous
HCl (0.5 mL), and the reaction was stirred at room tempera-
ture for 13 h. The mixture was evaporated to remove THF,
treated with saturated aqueous NaHCO3 (50 mL), and ex-
tracted with EtOAc (2 × 30 mL). The extracts were combined,
washed with brine (30 mL), dried with Na2SO4, and concen-
trated to give a solid (28 mg), which was dissolved in dry
dichloromethane (10 mL). To the dichloromethane solution was
added successively triethylamine (220 mg, 2.17 mmol) and
i-Pr3SiOTf (267 mg, 0.87 mmol), and the mixture was stirred
at room temperature under argon. After 14 h, the mixture was
diluted with 1 N aqueous HCl (30 mL) and extracted with
ether (2 × 30 mL). The extracts were combined, washed
successively with saturated aqueous NaHCO3 (30 mL) and
brine (30 mL), dried with Na2SO4, concentrated, and purified
by preparative GPC (J AIGEL-1H, 2 × 20 mm φ × 600 mm,
chloroform) to give 44 mg (72%, two steps) of 19 as a 60:40
mixture of stereoisomers, which was further purified by
preparative HPLC (LiChrosorb Si60, 10 mm φ × 250 mm,
ether/hexane) to afford colorless amorphous dl-19 and meso-
19. dl-19: 1H NMR (400 MHz, CD2Cl2) δ 1.09 (br s, 84 H), 4.20
(d, J ) 10.4 Hz, 4 H), 4.28 (d, J ) 10.4 Hz, 4 H), 6.87 (s, 4 H),
7.26-7.30 (m, 4 H), 7.35-7.39 (m, 4 H); 13C NMR (100 MHz,
CDCl3) δ 12.50, 18.35, 61.83, 66.35, 88.85, 94.47, 126.62,
4 H); 13C NMR (75 MHz, CD2Cl2) δ 12.51, 18.27, 18.30, 64.02,
94.57, 95.86, 121.58, 128.60, 128.63, 129.50, 130.14, 142.01;
IR (KBr) 2936, 2860, 1102 cm-1; UV (CH2Cl2) λmax 291 nm (ꢀ
33 000); fluorescence (CH2Cl2, λex ) 290 nm) λem ) 469 nm;
MS (FD) m/z 1144 (M+, 100); HRMS calcd for C72H104O4Si4
1144.7012, found 1144.6997.
X-r a y str u ctu r e d eter m in a tion for 5: C14H16O2Cl2, Mr
) 287.2, colorless cube (0.40 × 0.40 × 0.40 mm3), orthorhombic,
space group Pbca, a ) 16.093(5), b ) 20.07(1), c ) 8.587(3) Å,
V ) 2773(1) Å3, Dc ) 1.375 g cm-3, Z ) 8, Mo KR radiation (λ
) 0.71069 Å), T ) 296 K, µ ) 4.59 cm-1, F(000) ) 1200. A
total of 3605 unique reflections were collected, of which 2200
observed reflections [I > 2σ(I)] were used in the structure
solution (direct methods) and refinement (full-matrix least-
squares with 163 parameters) to give final R ) 0.086 and wR
) 0.080. Residual electron density is 0.79 e Å-3
.
X-r a y str u ctu r e d eter m in a tion for 13: C80H88O4Si4, Mr
) 1225.9, colorless plate (0.60 × 0.30 × 0.05 mm3), triclinic,
space group P1 bar, a ) 12.926(1), b ) 17.570(2), c ) 8.074(1)
Å, R ) 93.356(4)°, â ) 97.690(3)°, γ ) 79.755(4)°, V ) 1787.1-
(3) Å3, Dc ) 1.14 g cm-3, Z ) 1, Mo KR radiation (λ ) 0.71069
Å), T ) 203 K, µ ) 1.31 cm-1, F(000) ) 656. A total of 7513
unique reflections were collected, of which 5339 observed
reflections [I > 3σ(I)] were used in the structure solution (direct
methods) and refinement (full-matrix least-squares with 398
parameters) to give final R ) 0.063 and wR ) 0.069. Residual
electron density is 0.45 e Å-3
.
X-r a y str u ctu r e d eter m in a tion for a n ti-20: C72H104O4-
Si4, Mr ) 1144.7, colorless block (0.50 × 0.25 × 0.25 mm3),
triclinic, space group P1 bar, a ) 14.1929(4), b ) 20.3494(5),
c ) 13.1721(4) Å, R ) 105.252(1)°, â ) 100.2988(6)°, γ )
79.896(2)°, V ) 3578.0(2) Å3, Dc ) 1.064 g cm-3, Z ) 2, Mo KR
radiation (λ ) 0.71069 Å), T ) 203 K, µ ) 1.26 cm-1, F(000) )
1248. A total of 15541 unique reflections were collected, of
which 10152 observed reflections [I > 2σ(I)] were used in the
structure solution (direct methods) and refinement (full-matrix
least-squares with 721 parameters) to give final R ) 0.083 and
128.45, 131.03, 136.76, 145.99; IR (KBr) 2936, 2860, 1102 cm-1
;
MS (FD) m/z 1144 (M+, 100). meso-19: 1H NMR (400 MHz,
CD2Cl2) δ 1.10 (br s, 84 H), 4.20 (d, J ) 10.4 Hz, 4 H), 4.26 (d,
J ) 10.4 Hz, 4 H), 6.90 (s, 4 H), 7.26-7.30 (m, 4 H), 7.35-
7.39 (m, 4 H); 13C NMR (100 MHz, CDCl3) δ 12.50, 18.35, 61.83,
66.34, 88.60, 94.58, 126.54, 128.45, 131.02, 136.83, 146.32; IR
(KBr) 2936, 2860, 1102 cm-1; MS (FD) m/z 1144 (M+, 100).
Ma cr ocycle a n ti-20. A solution of dl-19 (16.2 mg, 0.014
mmol) in dichloromethane (14 mL) was placed in a Pyrex test
tube (18 mm × 18 cm), bubbled with argon for 15 min at 0 °C,
and irradiated with a high-pressure Hg lamp at 12 °C. The
reaction was monitored by HPLC, which showed the formation
of a single product. After 55 min (100% conversion), the
irradiation was terminated. The mixture was evaporated and
purified by preparative GPC (J AIGEL-1H, 2 × 20 mm φ ×
600 mm, chloroform) to give 12.0 mg (74%) of anti-20 as a
wR ) 0.080. Residual electron density is 0.40 e Å-3
.
Ack n ow led gm en t. We thank Professor Tamotsu
Inabe (Hokkaido University) for the use of X-ray ana-
lytical facilities. This work was supported in part by a
Grant-in-Aid for Scientific Research (09640620) from the
Ministry of Education, Science, Sports, and Culture of
J apan.
1
Su p p or tin g In for m a tion Ava ila ble: Copies of H NMR
spectra of compounds 9-13 and 17-20 and X-ray crystal-
lographic reports for 5, 13, and 20. This material is available
free of charge via the Internet at http://pubs.acs.org.
1
colorless powder: mp 152 °C (dec); H NMR (300 MHz, CD2-
Cl2) δ 1.14 (m, 84 H), 4.62 (d, J ) 13.2 Hz, 4 H), 4.95 (d, J )
13.2 Hz, 4 H), 7.25 (s, 4 H), 7.34-7.37 (m, 4 H), 7.46-7.50 (m,
J O0002590