Intermolecular [4 + 2] cycloaddition of o-quinodimethanes derived from ene-bis(sulfinylallenes)

Article abstract of DOI:10.1021/jo061014b

Intermolecular [4 + 2] cycloaddition of o-quinodimethanes, prepared in situ from ene-bis(propargyl alcohols) and benzenesulfenyl chloride via ene-bis(sulfinylallene) formation, was investigated. Benzene-bridged bis(propargyl alcohols) reacted with both el

Full text of DOI:10.1021/jo061014b

Intermolecular [4 + 2] Cycloaddition of o-Quinodimethanes Derived
from Ene-Bis(sulfinylallenes)
Shinji Kitagaki,* Kumiko Katoh, Kazuhiro Ohdachi, Yuji Takahashi, Daisuke Shibata, and
Chisato Mukai*
DiVision of Pharmaceutical Sciences, Graduate School of Natural Science and Technology,
Kanazawa UniVersity, Kakuma-machi, Kanazawa 920-1192, Japan
cmukai@kenroku.kanazawa-u.ac.jp; kitagaki@p.kanazawa-u.ac.jp
ReceiVed May 17, 2006
Intermolecular [4 + 2] cycloaddition of o-quinodimethanes, prepared in situ from ene-bis(propargyl
alcohols) and benzenesulfenyl chloride via ene-bis(sulfinylallene) formation, was investigated. Benzene-
bridged bis(propargyl alcohols) reacted with both electron-deficient and electron-rich olefins to give the
corresponding [4 + 2] cycloadducts. Ethylene-bridged bis(propargyl alcohols) underwent similar
cycloaddition with electron-deficient olefins. Construction of some heterocycles based on the newly
developed sequential reaction is also described.
Introduction
temperature or below)3 compared to the other reported proce-
dures. Nevertheless, little attention has so far been paid to the
chemistry of the ene-diallenes. Recent efforts in this laboratory
disclosed a novel one-pot synthesis of the polycyclic aromatic
compounds based on the sequential pericyclic reaction of the
ene-bis(sulfinylallene) intermediates 3, derived from the ene-
bis(propargyl alcohol) 1 and benzenesulfenyl chloride (PhSCl)
via the ene-bis(propargyl sulfenate) 2.4 Thus, the consecutive
sequences, which entirely involve the sulfenic ester formation
(first step), dual [2,3]-sigmatropic rearrangement of 2 (second
step),5,6 6π-electrocyclic reaction of ene-diallenes 3 (third step),
and finally intramolecular [4 + 2] cycloaddition of o-quin-
odimethanes 4 (fourth step), enabled the one-pot construction
of the polycyclic compounds 5 from the acyclic substrates 1
Inter- and intramolecular [4 + 2] cycloaddition reactions are
extremely useful processes for rapid assembly of complex
polycyclic systems.1 The o-quinodimethane intermediates have
been widely utilized as a powerful diene counterpart in the
cascade-based synthesis of polycyclic aromatic compounds.2 The
hitherto known methods for the generation of the o-quin-
odimethane species include thermolysis of benzocyclobutenes,
thermal cheletropic extrusion of small-sized molecules, and 1,4-
elimination of R,R′-substituted o-xylenes. These conventional
procedures generally require a considerably high reaction
temperature and/or a multiple-step route for the preparation of
the precursors for the o-quinodimethanes.
On the other hand, ene-diallenes had been shown to be
rapidly transformed into the o-quinodimethanes via the 6π-
electrocyclic reaction under much milder conditions (at room
(3) (a) Tanaka, K.; Takamoto, N.; Tezuka, Y.; Kato, M.; Toda, F.
Tetrahedron 2001, 57, 3761-3767. (b) Toda, F.; Tanaka, K.; Sano, I.;
Isozaki, T. Angew. Chem., Int. Ed. Engl. 1994, 33, 1757-1758. (c)
Sugimoto, Y.; Hanamoto, T.; Inanaga, J. Appl. Organomet. Chem. 1995,
9, 369-375. (d) Inanaga, J.; Sugimoto, Y.; Hanamoto, T. Tetrahedron Lett.
1992, 33, 7035-7038. (e) Ezcurra, J. E.; Moore, H. W. Tetrahedron Lett.
1993, 34, 6177-6180. (f) Braverman, S.; Duar, Y. J. Am. Chem. Soc. 1990,
112, 5830-5837. (g) Ho¨hn, J.; Weyerstahl, P. Chem. Ber. 1983, 116, 808-
814. (h) Staab, H. A.; Draeger, B. Chem. Ber. 1972, 105, 2320-2333. (i)
Bowes, C. M.; Montecalvo, D. F.; Sondheimer, F. Tetrahedron Lett. 1973,
3181-3184. (j) Ben-Efraim, D. A.; Sondheimer, F. Tetrahedron Lett. 1963,
313-315.
* To whom correspondence should be addressed. Tel: +81-76-234-4411.
Fax: +81-76-234-4410.
(1) (a) Takao, K.; Munakata, R.; Tadano, K. Chem. ReV. 2005, 105,
4779-4807. (b) Nicolaou, K. C.; Snyder, S. A.; Montagnon, T.; Vassil-
ikogiannakis, G. Angew. Chem., Int. Ed. 2002, 41, 1668-1698. (c) Corey,
E. J. Angew. Chem., Int. Ed. 2002, 41, 1650-1667. (d) Fringuelli, F.;
Taticchi, A. The Diels-Alder Reaction: Selected Practical Methods; John
Wiley & Sons: Chichester, West Sussex, 2002.
(2) (a) Segura, J. L.; Martin, N. Chem. ReV. 1999, 99, 3199-3246. (b)
Martin, N.; Seoane, C.; Hanack, M. Org. Prep. Proc. Int. 1991, 23, 237-
272. (c) Charlton, J. L. Alauddin, M. M. Tetrahedron 1987, 43, 2873-
2889. (d) Oppolzer, W. Synthesis 1978, 793-802.
(4) Kitagaki, S.; Ohdachi, K.; Katoh, K.; Mukai, C. Org. Lett. 2006, 8,
95-98.
(5) Horner, L.; Binder, V. Liebigs Ann. Chem. 1972, 757, 33-68.
10.1021/jo061014b CCC: $33.50 © 2006 American Chemical Society
Published on Web 08/11/2006
6908
J. Org. Chem. 2006, 71, 6908-6914

Intermolecular [4 + 2] Cycloaddition of o-Quinodimethanes
TABLE 1. Reaction of Benzene-Bridged Bis(propargyl alcohol) 6
with 7aa
SCHEME 1
entry
ArSX
PhSCl
PhSCl
PhSCl
PhSCl
PhSCl
4-NO2C6H4SCl
PhSSO2Ph
base
solvent
yield of 11 (%)
1
2
3
4
5
6
7
Et3N
THF
THF
THF
toluene
CH2Cl2
THF
84
84
33
76
44
0
iPr2NEt
pyridine
Et3N
Et3N
Et3N
Et3N
(Scheme 1). The efficiency of the newly developed method has
been verified by a convenient synthesis of the estra-1,3,5(10)-
trien-17-one.4 We have now investigated the intermolecular
[4 + 2] cycloaddition between the o-quinodimethanes, generated
from ene-bis(sulfinylallene) species, and several dienophiles.
In this paper, the details of the successful application of this
methodology to the intermolecular version is described.7
THF
0
a All reactions were performed on a 0.2 mmol scale (0.08 M) with 6
equiv of ArSX, 7 equiv of base, and 2 equiv of 7a.
By using the optimized conditions described above (Et3N,
THF), the sequential reaction of benzene-bridged bis(propargyl
alcohols) 6 and 12 with various dienophiles were investigated
(Table 2). Cycloaddition of 6 with dimethyl maleate (7b) gave
the cis-adduct 11b in 24% yield along with a trace amount of
trans-adduct 11a (entry 2).9,10 Neither dimethyl maleate or
product 11b isomerized to the corresponding trans-isomers under
the reaction conditions.11 These results strongly suggest that the
[4 + 2]-type cycloaddition between the o-quinodimethane 9 and
maleate 7b must have proceeded at least in part in a noncon-
certed fashion. On the other hand, other electron-deficient olefins
7c-e and styrene (7f) provided the corresponding cycloadducts
in good yields (entries 3-6). Interestingly, the electron-rich
olefin 7g also took part in the cycloaddition reaction to afford
11g, although a prolonged reaction time and a large excess of
7g were required (entry 7). In addition, a slightly lower yield
(72%) of 13, compared to that of 11a, was observed when the
bis(propargyl alcohol) derivative, having a methyl group at the
C-3 position on the benzene ring, was exposed to the standard
conditions (entry 8 vs 1). To summarize the results obtained in
Table 2, the o-quinodimethane intermediate 9 reacts with a
variety of dienophiles irrespective of the property of the olefinic
counterpart, although it is obvious that the electron-deficient
olefin has a much higher reactivity than the electron-rich ones.
Results and Discussion
We first examined a tandem ene-diallene/o-quinodimethane
formation from benzene-bridged bis(propargyl alcohol) 68 and
subsequent [4 + 2] cycloaddition with dimethyl fumarate (7a).
The reaction was performed as follows. PhSCl was added to a
solution of 6 and 7a in the presence of a base at -78 °C and
then warmed to room temperature for 2 h. After the usual
workup and a subsequent short column chromatography, the
crude products were treated with m-CPBA in CH2Cl2 to simplify
structure determination of the cycloadduct. The results are
summarized in Table 1. Reaction using Et3N as a base in THF
provided the desired cycloadduct 11a in 84% yield (entry 1).4
While a similar result was obtained using Hunig’s base (entry
2), pyridine provided a rather low yield (entry 3). Of the solvents
surveyed using Et3N as a base, THF was found to be the optimal
solvent for this transformation (entries 1, 4, and 5). Reaction
with 4-nitrobenzenesulfenyl chloride gave a complex mixture
of products (entry 6), and no reaction occurred when S-phenyl
benzenethiosulfate was used (entry 7).
(6) The tandem formation and intramolecular [4 + 2] cycloaddition of
1-sulfinyl-1-vinylallenes, triggered by [2,3]-sigmatropic rearrangement of
the corresponding propargyl sulfenates, have been reported: (a) Okamura,
W. H.; Curtin, M. L. Synlett 1990, 1-9. (b) Curtin, M. L.; Okamura, W.
H. J. Org. Chem. 1990, 55, 5278-5287. (c) Gibbs, R. A.; Bartels, K.; Lee,
R. W. K.; Okamura, W. H. J. Am. Chem. Soc. 1989, 111, 3717-3725. (d)
Gibbs, R. A.; Okamura, W. H. J. Am. Chem. Soc. 1988, 110, 4062-4063.
(7) The intermolecular cycloaddition reaction of the o-quinodimethane
derived from cis-4-octene-2,6-diyne-1,8-diol and PhSCl was described in
the review article by Grissom (Grissom, J. W.; Gunawardena, G. U.;
Klingberg, D.; Huang, D. Tetrahedron 1996, 52, 6453-6518). However,
no original manuscript dealing with the details of this reaction is available.
(8) Basak, A.; Shain, J. C.; Khamrai, U. K.; Rudra, K. R.; Basak, A. J.
Chem. Soc., Perkin Trans. 1 2000, 1955-1964.
(9) Stereochemistry of cycloadduct 11b was determined to be cis by the
chemical correlation with the sole cyclized product, which was obtained
from 6 and maleic anhydride by the following successive reaction: (1) 6,
PhSCl, Et3N, maleic anhydride, THF, -78 °C to rt, then 10% HCl; (2)
TMSCHN2, MeOH; (3) m-CPBA, CH2Cl2.
(10) For the low reactivity of maleate esters for dienes, see: Lenihan,
B. D.; Shechter, H. J. Org. Chem. 1998, 63, 2072-2085 and references
therein.
(11) There are some examples where cycloadditions of o-quin-
odimethanes with maleate esters give mixtures of cis- and trans-cycloadducts
due to the isomerization of maleates prior to the cycloaddition process
occurring: (a) Reference 10. (b) Inaba, S.; Wehmeyer, R. M.; Forkner, M.
W.; Rieke, R. D. J. Org. Chem. 1988, 53, 339-344. See also ref 3c.
J. Org. Chem, Vol. 71, No. 18, 2006 6909

Kitagaki et al.
TABLE 2. Reaction of Benzene-Bridged Bis(propargyl alcohols)
with Various Dienophilesa
TABLE 3. Reaction of Ethylene-Bridged Bis(propargyl alcohols)
14 with Various Dienophilesa
a All reactions were performed on a 0.2 mmol scale (0.08 M) with 4-6
equiv of PhSCl, 5-7 equiv of Et3N, and 2-5 equiv of dienophile. b After
a solution of 14, Et3N, and PhSCl was stirred at -78 °C for 1 h, 7a was
added to the mixture, which was stirred at -78 °C for 1 h and at room
temperature for 2 h. c After a solution of 14, Et3N, and PhSCl was stirred
at -78 °C for 1 h and at 0 °C for 1 h, 7a was added to the mixture, which
was stirred at room temperature for 2 h. d Reaction was performed in the
presence of BHT (2 equiv). e Reaction was performed in the presence of
TEMPO (2 equiv).
yield in the reaction of 14 with 7e (entries 7 and 8). The fact
that the effect of a radical scavenger was remarkable when the
long-stored PhSCl13 was used indicates that the radical scavenger
might partially inhibit the side reactions due to the thiyl radical,
derived from sulfenyl chloride.14 Unfortunately, cycloaddition
of 14 with electron-rich olefins did not occur, which might be
predictable on the basis of the results in Table 2. As mentioned
in the reaction of 6 with 7g, the electron-rich olefin has less
reactivity for [4 + 2] cycloaddition and needs a prolonged
reaction time. Therefore, the reaction of the electron-rich olefin
with the o-quinodimethane, derived from 14, would be consid-
ered to require a rather long reaction time that must have caused
the decomposition of the quinodimethane intermediate. Experi-
ments with entries 2 and 3 may indirectly support the above
considerations. Namely, addition of PhSCl to the mixture of
a Reactions were performed according to the procedure described in
footnote a of Table 1, unless otherwise stated. b Reaction was performed
with 5 equiv of 7d. c Reaction was performed with 6 equiv of 7f. d Reaction
mixture was stirred at -78 °C for 1.5 h and then at room temperature for
17 h after addition of PhSCl. e Reaction was performed with 10 equiv of
7g.
Reaction of the ethylene-bridged bis(propargyl alcohol) 1412
with various dienophiles was the next subject to examine (Table
3). The reaction of 14 with the electron-deficient olefins 7a,
7c-e, and 7h resulted in the formation of the polycyclic
products in slightly decreased yields compared to those for 6
(entries1-9). Interestingly, it was found that the addition of
BHT or TEMPO in the reaction mixture led to an increase in
(13) PhSCl was prepared by a literature procedure and stored in the
freezer: Barrett, A. G. M.; Dhanak, D.; Graboski, G. G.; Taylor, S. J. Org.
Synth. 1990, 68, 8-12.
(14) Davies, M. J.; Hawkins, C. L. Free Radic. Res. 2000, 33, 719-
729.
(12) Mladenova, M.; Alami, M.; Linstrumelle, G. Synth. Commun. 1996,
26, 2831-2842.
6910 J. Org. Chem., Vol. 71, No. 18, 2006

Intermolecular [4 + 2] Cycloaddition of o-Quinodimethanes
SCHEME 2
SCHEME 3
SCHEME 4
14, Et3N, and dienophile 7a at -78 °C and then raising the
reaction temperature to 0 °C (standard conditions) afforded 15a
in 73% yield (entry 1). When a solution of 14, Et3N, and PhSCl
was stirred at -78 °C for 1 h, followed by addition of 7a, 15a
was obtained in 56% yield (entry 2), while addition of 7a to
the reaction mixture at 0 °C instead of -78 °C gave 15a in
only 8% yield (entry 3). This is not the case in the reaction of
benzene-bridged bis(propargyl alcohol) 6 with 7a.
Thus, it turns out that the reactivity of the o-quinodimethane
derived from the olefinic compound 14 toward the dienophiles
was generally lower than that of the o-quinodimethane 9 having
a benzene ring. We next became interested in the effects of
substituents on the ethylene moiety of 14 in the [4 + 2]
cycloaddition reaction. Thus, bis(propargyl alcohol) 17, bearing
siloxymethyl-substituted ethylene, was prepared in a five-step
procedure including stepwise Negishi coupling15 from the known
ethyl (Z)-dibromopropenoate (16)16 as depicted in Scheme 2.
The sequential reaction of 17 with 7a under the standard
conditions gave the expected cycloadduct 18, but the chemical
yield was rather low (38%). Alternatively, bis(propargyl alco-
hols) 23 and 24 containing five- and six-membered carbocycles,
respectively, were synthesized from cycloalkanones 19 and 20
via 2-(3-siloxypropynyl)-1-cycloalkenecarbaldehydes 21 and
2217 by taking advantage of the consecutive Vilsmeier reaction,
Sonogashira coupling,18 and Corey-Fuchs alkynylation19 (Scheme
3). With the two additional bis(propargyl alcohols) 23 and 24
in hand, we examined the sequential pericyclic reaction of 23
and 24 with 7a under the standard conditions to provide the
cycloadducts 25 and 26 in 48 and 57% yields, respectively. In
comparison with the result in Table 3, entry 1, these three
examples show a decrease in the chemical yields of the desired
products, which may be attributable to the nonbonding interac-
tion between a phenylsulfonyl group and a substituent such as
the TBDPSOCH2 group in 18 and the methylene side chain in
25 and 26. This would not be the case with 15a where no similar
nonbonding interaction could be predicted.
Next, three types of heterocycle-containing ene-diallenes
were examined. Indole-containing substrate 29 was synthesized
starting from iodination at the C-2 position of N-methoxym-
ethylindole-3-carbaldehyde (27)20 (Scheme 4). According to the
aforementioned procedure in Scheme 3, introduction of the bis-
(propargyl alcohol) unit to the 2-iodo derivative of 27 was
realized via 28 to furnish the desired 29.
Treatment of 29 with 7a gave the cycloadduct 30 in 55%
yield after m-CPBA oxidation in the presence of NaHCO3.
Furan-containing substrate 33 was prepared by a procedure
similar to that described in Scheme 4, except for the protection
of the formyl group (Scheme 5).21 Cycloaddition of 33 with 7a
under the standard conditions gave 34 in a low yield.
Pyrazine-containing substrate 36 was also prepared by dual
Sonogashira coupling of readily available diiodopyrazine 3522
and 3-siloxypropyne (Scheme 6). Treatment of 36 with PhSCl
(15) King, A. O.; Negishi, E.; Villani, F. J., Jr.; Silveira, A., Jr. J. Org.
Chem. 1978, 43, 358-360.
(16) (a) Myers, A. G.; Alauddin, M. M.; Fuhry, M. A. M.; Dragovich,
P. S.; Finney, N. S.; Harrington, P. M. Tetrahedron Lett. 1989, 30, 6997-
7000. (b) Hall, R. G.; Trippett, S. Tetrahedron Lett. 1982, 23, 2603-2604.
(17) (a) Herndon, J. W.; Wang, H. J. Org. Chem. 1998, 63, 4562-4563.
(b) Arnold, Z.; Holy, A. Collect. Czech. Chem. Commun. 1961, 26, 3059-
3073.
(20) Comins, D. L.; Killpack, M. O. J. Org. Chem. 1987, 52, 104-109.
(21) Mukai, C.; Hirose, T.; Teramoto, S.; Kitagaki, S. Tetrahedron 2005,
61, 10983-10994.
(22) Ple´, N.; Turck, A.; Heynderickx, A.; Que´guiner, G. Tetrahedron
1998, 54, 9701-9710.
(18) Sonogashira, K.; Tohda, Y.; Hagihara, N. Tetrahedron Lett. 1975,
4467-4470.
(19) Corey, E. J.; Fuchs, P. L. Tetrahedron Lett. 1972, 3769-3772.
J. Org. Chem, Vol. 71, No. 18, 2006 6911

Kitagaki et al.
TABLE 4. Reaction of Methyl-Substituted Bis(propargyl alcohols)
38 with 7a
SCHEME 5
yield (%)
entry
substrate
R
T (°C)/time (h)
40
42
44
1
2
3
4
38a
38a
38b
38b
H
H
Me
Me
-78/2 f rt/2
38a
42b
0
trace
9
15
0
0
38
42
rt/0.5 f reflux/15
-78/2 f rt/2
rt/0.5 f reflux/15
0
15
a Product was obtained as a mixture of diastereomers (ratio not
determined). b Product was obtained as a mixture of diastereomers in a ratio
of 2:1.
SCHEME 6
SCHEME 7
in the presence of 7a provided 37 in high yield as a separable
mixture of two diastereomers in a ratio of 5:4, due to the chirality
of the sulfinyl group. Simple oxidation of 37 with m-CPBA to
the corresponding sulfonyl derivative was unsuccessful and gave
a complex mixture of several products, presumably due to
undesired oxidation of the amine functionalities. Thus, the
pyrazine derivative 36 afforded the cyclized product 37 in a
satisfactory yield, while the indole derivative 29 resulted in the
formation of 30 in a moderate yield. On the other hand, the
furan derivative 33 led to the low yield of 34. We do not yet
have a reasonable clue to understanding the difference in
chemical yield observed between these three compounds in
combination with the benzene derivative 11a.
Finally, the effect of substituents at the propargylic position
of ene-bis(propargyl alcohols) was studied. Monomethyl-
substituted bis(propargyl alcohol) 38a was exposed to PhSCl
in the presence of 7a to afford cycloadduct 40a in 38% yield
(Table 4, entry 1). Higher reaction temperature (reflux in THF)
led to a slight improvement in the yield of 40a along with an
increase in the [1,5] hydrogen-shift product 42a (entry 2).23
Dimethyl-substituted derivative 38b12 no longer gave the [4 +
2] product 40b but rather the benzocyclobutene derivative 44b
(38-42% yield), which should have arisen from the intramo-
lecular [2 + 2] cycloaddition reaction, along with 42b (15%
yield) (entries 3 and 4). Upon treatment with PhSCl under the
standard conditions, the benzene-bridged bis(propargyl alcohol)
45, possessing a methyl group at the propargyl position, gave
the [2 + 2] cycloadduct 46 (43%) as well as the [1,5] hydrogen-
shift product 47 (14%), but not the [4 + 2] cycloadduct (Scheme
7). This result is in contrast to those observed in the reaction of
6 with 7a where the corresponding tetrahydroanthracene deriva-
tives ([4 + 2] products) could be obtained as a major product.
In summary, we have demonstrated that benzene-bridged bis-
(sulfinylallenes), derived from the ene-bis(propargyl alcohols),
underwent an intermolecular [4 + 2] cycloaddition with various
dienophiles to give polycyclic aromatic compounds. Application
of this method to the ethylene-bridged bis(sulfinylallenes) was
realized. In addition, ene-bis(sulfinylallenes) having one or two
methyl group at the allenic termini were shown to collapse to
form the cyclobutene derivatives and/or the [1,5] hydrogen-
shift products. The present reaction system allows considerable
structural variations in the “ene” part of the ene-diallene such
as benzene, ethylene, and heterocycles.
Experimental Section
Sequential Pericyclic Reaction of Ene-Bis(propargyl alco-
hols): General Procedure. To a solution of bis(propargyl alcohol)-
(0.200 mmol) in THF (3.0 mL) were successively added dienophile
(0.400 mmol), Et3N (0.20 mL, 1.4 mmol), and a solution of PhSCl
(175 mg, 1.20 mmol) in THF (0.5 mL) at -78 °C. After being
stirred for 2 h, the reaction mixture was allowed to warm to room
temperature. After 2 h, the reaction was quenched by addition of
water, and the mixture was extracted with AcOEt. The extract was
washed with water and brine, dried, and concentrated to dryness.
The residue was passed through a short pad of silica gel to afford
the crude sulfoxide. To a solution of the crude sulfoxide in CH2-
Cl2 (2 mL) was added m-CPBA (82.8 mg, 0.480 mmol) at 0 °C,
and the reaction mixture was allowed to warm to room temperature.
(23) In the study of intramolecular [4 + 2] cycloaddition on the basis of
this methodology, improvement in the cycloadduct yield was observed when
a reaction mixture was heated under reflux. See ref 4.
6912 J. Org. Chem., Vol. 71, No. 18, 2006

Intermolecular [4 + 2] Cycloaddition of o-Quinodimethanes
After 12 h, the reaction was quenched by addition of saturated
aqueous Na2S2O3 and aqueous NaHCO3, and the mixture was
extracted with CH2Cl2. The extract was washed with water and
brine, dried, and concentrated to dryness. Chromatography of the
residue gave 11.
Dimethyl trans-5,8-bis(phenylsulfonyl)-1,2,3,4-tetrahydronaph-
thalene-2,3-dicarboxylate (15a): colorless powder; mp 198-200
°C (acetone-hexane); IR 1736, 1319, 1138 cm-1; 1H NMR δ 8.23
(2H, s), 7.87-7.48 (10H, m), 3.62 (6H, s), 3.48-3.40 (2H, m),
3.06-2.87 (4H, m); 13C NMR δ 173.2, 143.6, 139.7, 136.8, 133.9,
129.4, 128.0, 127.7, 52.3, 39.7, 27.8; MS m/z 528 (M+, 7.2). Anal.
Calcd for C26H24O8S2: C, 59.08; H, 4.58. Found: C, 58.96; H,
4.60.
Dimethyl cis-9,10-bis(phenylsulfonyl)-1,2,3,4-tetrahydroan-
thracene-2,3-dicarboxylate (11b): pale yellow oil; IR 1734, 1308,
1
1150 cm-1; H NMR δ 9.10-9.03 (2H, m), 7.96-7.82 (4H, m),
7.62-7.46 (8H, m), 4.14 (2H, dd, J ) 17.2, 5.3 Hz), 3.62 (6H, s),
3.51 (2H, dd, J ) 17.2, 8.9 Hz), 3.02-2.93 (2H, m); 13C NMR δ
172.7, 143.0, 139.9, 138.9, 133.4, 130.0, 129.4, 127.6, 126.1, 125.3,
52.1, 39.9, 29.1; MS m/z 578 (M+, 6.1); HRMS calcd for
C30H26O8S2 578.1069, found 578.1064.
N-Phenyl-5,8-bis(phenylsulfonyl)-1,2,3,4-tetrahydronaphtha-
lene-2,3-dicarboximide (15c): colorless powder; mp 280.5-282.5
°C (CH2Cl2-AcOEt-hexane); IR 1717, 1321, 1140 cm-1; 1H NMR
δ 8.30 (2H, s), 7.90-7.89 (4H, m), 7.61-7.58 (2H, m), 7.53-
7.50 (4H, m), 7.37-7.32 (3H, m), 6.97-6.96 (2H, m), 3.61-3.57
(2H, m), 3.19-3.15 (2H, m), 2.95-2.93 (2H, m); 13C NMR δ 175.9,
143.8, 140.2, 138.6, 133.9, 131.3, 129.6, 128.9, 128.5, 128.1, 127.8,
126.0, 38.7, 25.9; MS m/z 557 (M+, 7.3). Anal. Calcd for C30H23-
NO6S2: C, 64.62; H, 4.16; N, 2.51. Found: C, 64.46; H, 4.16; N,
2.50.
5,8-Bis(phenylsulfonyl)-1,4-anthraquinone (15d): yellow pow-
der; mp 289-291 °C dec (CHCl3-hexane); IR 1680, 1614, 1317,
1150 cm-1; 1H NMR δ 9.48 (2H, s), 8.82 (2H, s), 8.09-8.05 (4H,
m), 7.60-7.51 (6H, m), 7.09 (2H, s); 13C NMR δ 183.1, 144.2,
139.9, 134.2, 130.9, 130.6, 129.7, 128.1, 125.6; FABMS m/z 489
(M+ + 1, 5.6); FABHRMS calcd for C26H17O6S2 489.0467, found
489.0493.
N-Phenyl-9,10-bis(phenylsulfonyl)-1,2,3,4-tetrahydroan-
thracene-2,3-dicarboximide (11c): pale yellow oil; IR 1717, 1327,
1
1308, 1150 cm-1; H NMR δ 9.06-9.00 (2H, m), 7.94 (4H, d, J
) 7.3 Hz), 7.60-7.29 (11H, m), 6.99 (2H, dd, J ) 7.3, 1.3 Hz),
4.02-3.80 (4H, m), 3.23-3.13 (2H, m); 13C NMR δ 176.4, 142.6,
139.8, 139.2, 133.6, 131.3, 130.1, 129.5, 129.0, 128.5, 128.0, 126.2,
126.0, 125.5, 39.0, 27.3; MS m/z 607 (M+, 35); HRMS calcd for
C34H25NO6S2 607.1123, found 607.1125.
6,11-Bis(phenylsulfonyl)-1,4-naphthacenequinone (11d): pale
1
yellow oil; IR 1682, 1296, 1153 cm-1; H NMR δ 9.99 (2H, s),
9.57-9.51 (2H, m), 8.01-7.97 (4H, m), 7.79-7.73 (2H, m), 7.60-
7.47 (6H, m), 7.10 (2H, s); 13C NMR δ 183.1, 143.0, 140.8, 140.5,
133.8, 132.4, 130.0, 129.6, 129.5, 127.9, 126.8, 126.5, 125.4; MS
m/z 538 (M+, 10); HRMS calcd for C30H18O6S2 538.0545, found
538.0543.
Methyl 5,8-bis(phenylsulfonyl)-1,2,3,4-tetrahydronaphthalene-
2-carboxylate (15e): colorless powder; mp 166-167 °C (CH2-
1
Cl2-AcOEt); IR 1732, 1310, 1138 cm-1; H NMR δ 8.26-8.21
Methyl 9,10-bis(phenylsulfonyl)-1,2,3,4-tetrahydroanthracene-
2-carboxylate (11e): pale yellow oil; IR 1734, 1325, 1304, 1148
(2H, m), 7.88-7.82 (4H, m), 7.65-7.52 (6H, m), 3.61 (3H, s),
3.45 (1H, dd, J ) 17.6, 5.3 Hz), 3.15 (1H, dt, J ) 16.1, 5.4 Hz),
2.85 (1H, dd, J ) 17.6, 9.3 Hz), 2.82-2.76 (1H, m), 2.53-2.47
(1H, m), 2.00-1.95 (1H, m), 1.69-1.61 (1H, m); 13C NMR δ 174.3,
143.9, 143.6, 139.9, 139.8, 138.4, 137.6, 133.81, 133.76, 129.33,
129.30, 128.1, 127.9, 127.33, 127.31, 51.9, 37.7, 28.6, 25.6, 23.8;
MS m/z 470 (M+, 23). Anal. Calcd for C24H22O6S2: C, 61.26; H,
4.71. Found: C, 60.93; H, 4.75.
1
cm-1; H NMR δ 9.13-9.00 (2H, m), 7.87 (2H, dd, J ) 7.3, 1.6
Hz), 7.82 (2H, dd, J ) 7.3, 1.6 Hz), 7.61-7.47 (8H, m), 3.90 (1H,
dd, J ) 15.5, 5.9 Hz), 3.65 (3H, s), 3.65-3.56 (1H, m), 3.42 (1H,
dd, J ) 15.5, 8.9 Hz), 3.28-3.17 (1H, m), 2.69-2.57 (1H, m),
2.01-1.88 (1H, m), 1.82-1.68 (1H, m); 13C NMR δ 175.2, 143.44,
143.38, 143.26, 141.5, 138.6, 137.7, 133.3, 133.2, 129.8, 129.7,
129.31, 129.29, 127.5, 127.4, 126.0, 125.9, 125.31, 125.27, 52.0,
36.9, 28.8, 25.9, 23.2; MS m/z 520 (M+, 19); HRMS calcd for
C28H24O6S2 520.1015, found 520.1013.
2-Cyano-5,8-bis(phenylsulfonyl)-1,2,3,4-tetrahydronaphtha-
1
lene (15h): colorless oil; IR 2245, 1321, 1140 cm-1; H NMR δ
8.23 (1H, d, J ) 8.8 Hz), 8.21 (1H, d, J ) 8.8 Hz), 7.86-7.83
(4H, m), 7.68-7.63 (2H, m), 7.59-7.54 (4H, m), 3.46 (2H, dd, J
) 7.6, 5.4 Hz), 3.18-3.08 (2H, m), 3.03-2.96 (1H, m), 2.84-
2.80 (1H, m), 2.03-2.00 (1H, m), 1.89-1.84 (1H, m); 13C NMR
δ 144.0, 143.9, 139.44, 139.36, 137.2, 134.7, 134.1, 134.0, 129.6,
129.4, 128.1, 127.90, 127.88, 127.75, 120.5, 29.3, 24.4, 24.2, 23.9;
MS m/z 437 (M+, 34); HRMS calcd for C23H19O4NS2 437.0756,
found 437.0759.
2-Phenyl-9,10-bis(phenylsulfonyl)-1,2,3,4-tetrahydroan-
1
thracene (11f): pale yellow oil; IR 1323, 1304, 1148 cm-1; H
NMR δ 9.18-9.07 (2H, m), 7.85 (2H, d, J ) 8.3 Hz), 7.72 (2H,
d, J ) 8.3 Hz), 7.59-7.40 (8H, m), 7.29-7.20 (3H, m), 7.03 (2H,
d, J ) 7.6 Hz), 4.02 (1H, dd, J ) 15.8, 5.0 Hz), 3.82 (1H, dt, J )
15.8, 5.9 Hz), 3.35-3.16 (2H, m), 2.78-2.67 (1H, m), 1.98-1.89
(2H, m); 13C NMR δ 145.9, 143.5, 143.2, 138.3, 138.0, 133.3,
133.2, 129.9, 129.8, 129.3, 128.6, 127.4, 126.8, 126.5, 125.9, 125.3,
125.2, 38.0, 35.0, 28.2, 27.3; MS m/z 538 (M+, 36); HRMS calcd
for C32H26O4S2 538.1273, found 538.1274.
Dimethyl trans-6-(tert-butyldiphenylsiloxy)methyl-5,8-bis(phen-
ylsulfonyl)-1,2,3,4-tetrahydronaphthalene-2,3-dicarboxylate
1
(18): colorless oil; IR 1736, 1317, 1138 cm-1; H NMR δ 8.96
2-Ethoxy-9,10-bis(phenylsulfonyl)-1,2,3,4-tetrahydroan-
(1H, s), 7.88-7.83 (2H, m), 7.66-7.33 (18H, m), 5.34 (2H, s),
3.64 (3H, s), 3.60 (3H, s), 3.45-2.79 (6H, m), 1.15 (9H, s); 13C
NMR δ 173.5, 173.4, 143.2, 142.6, 141.6, 140.2, 139.5, 139.1,
135.6, 135.5, 135.4, 133.7, 133.5, 132.9, 129.9, 129.4, 129.2, 128.0,
127.8, 127.1, 126.3, 63.3, 52.3, 52.2, 40.3, 39.7, 28.7, 27.7, 26.9,
19.3; FABMS m/z 796 (M+ + 1, 17). Anal. Calcd for C43H44O9S2-
Si: C, 64.80; H, 5.56. Found: C, 64.41; H, 5.69.
1
thracene (11g): pale yellow oil; IR 1325, 1304, 1148 cm-1; H
NMR δ 9.10-9.05 (1H, m), 8.96-8.91 (1H, m), 7.95 (2H, dd, J
) 7.3, 1.7 Hz), 7.82 (2H, dd, J ) 7.3, 1.7 Hz), 7.57-7.46 (8H,
m), 3.86-3.73 (2H, m), 3.62-3.49 (2H, m), 3.44-3.33 (2H, m),
3.25-3.14 (1H, m), 2.04-1.92 (1H, m), 1.60-1.47 (1H, m), 1.09
(3H, t, J ) 6.9 Hz); 13C NMR δ 144.2, 143.5, 143.3, 141.3, 138.7,
137.4, 133.2, 129.8, 129.3, 127.3, 127.2, 126.0, 125.9, 125.4, 125.2,
72.4, 63.7, 32.3, 27.9, 25.5, 15.4; MS m/z 506 (M+, 12); HRMS
calcd for C28H26O5S2 506.1221, found 506.1221.
Dimethyl trans-4,9-bis(phenylsulfonyl)-2,3,5,6,7,8-hexahydro-
1H-cyclopenta[b]naphthalene-6,7-dicarboxylate (25): colorless
1
oil; IR 1734, 1308, 1144 cm-1; H NMR δ 7.83-7.50 (10H, m),
Dimethyl trans-5-methyl-9,10-bis(phenylsulfonyl)-1,2,3,4-tet-
rahydroanthracene-2,3-dicarboxylate (13): pale yellow oil; IR
3.62 (6H, s), 3.67-3.15 (8H, m), 2.88-2.84 (2H, m), 2.11-2.03
(2H, m); 13C NMR δ 173.7, 146.9, 142.1, 139.2, 136.9, 133.5,
129.2, 126.6, 52.2, 40.1, 34.3, 28.2, 24.9; MS m/z 568 (M+, 14);
HRMS calcd for C29H28O8S2 568.1226, found 568.1202.
1
1734, 1317, 1310, 1159, 1150 cm-1; H NMR δ 8.75-8.71 (1H,
m), 7.88 (2H, d, J ) 7.6 Hz), 7.58-7.38 (10H, m), 4.04-3.97
(1H, m), 3.71 (3H, s), 3.71-3.04 (4H, m), 3.60 (3H, s), 2.97 (3H,
s), 2.52-2.44 (1H, m); 13C NMR δ 173.8, 173.4, 144.6, 142.9,
139.6, 139.3, 139.1, 137.8, 136.4, 133.3, 132.9, 130.8, 130.5, 130.0,
129.2, 128.9, 127.8, 126.8, 126.2, 121.8, 52.4, 39.9, 39.0, 28.6,
27.8, 26.0; MS m/z 592 (M+, 9.8); HRMS calcd for C31H28O8S2
592.1226, found 592.1227.
Dimethyl trans-9,10-bis(phenylsulfonyl)-1,2,3,4,5,6,7,8-octahy-
droanthracene-2,3-dicarboxylate (26): colorless oil; IR 1734,
1
1308, 1146 cm-1; H NMR δ 7.80-7.50 (10H, m), 3.66 (6H, s),
3.71-3.53 (4H, m), 3.04-3.00 (6H, m), 1.46-1.41 (4H, m); 13C
NMR δ 174.1, 143.3, 141.7, 140.7, 138.0, 133.1, 129.3, 126.0, 52.3,
J. Org. Chem, Vol. 71, No. 18, 2006 6913

Kitagaki et al.
40.4, 28.4, 27.1, 20.0; MS m/z 582 (M+, 11); HRMS calcd for
C30H30O8S2 582.1382, found 582.1410.
35.3, 33.2, 32.1, 26.7, 25.9, 22.1, 16.3; MS m/z 542 (M+, 25);
HRMS calcd for C27H26O8S2 542.1069, found 542.1065.
2-Ethenyl-3-methyl-1,4-bis(phenylsulfonyl)benzene (42a): col-
Dimethyl trans-5-(methoxymethyl)-6,11-bis(phenylsulfonyl)-
7,8,9,10-tetrahydro-5H-benzo[b]carbazole-8,9-dicarboxylate
1
orless oil; IR 1319, 1138 cm-1; H NMR δ 8.34 (1H, d, J ) 8.6
1
(30): colorless oil; H NMR δ 8.81 (1H, d, J ) 8.4 Hz), 7.88-
Hz), 8.30 (1H, d, J ) 8.6 Hz), 7.87-7.77 (4H, m), 7.67-7.39 (6H,
m), 6.68 (1H, dd, J ) 18.2, 11.6 Hz), 5.44 (1H, dd, J ) 11.6, 1.3
Hz), 4.77 (1H, dd, J ) 18.2, 1.3 Hz), 2.35 (3H, s); 13C NMR δ
144.4, 143.9, 141.3, 140.6, 140.1, 138.4, 133.7, 133.5, 131.2, 129.3,
128.8, 128.4, 128.2, 128.0, 126.7, 123,5, 17.5; FABMS m/z 399
(M+ + 1, 100); FABHRMS calcd for C21H19O4S2 399.0725, found
399.0713.
7.22 (13H, m), 5.99 (2H, s), 3.66 (3H, s), 3.66-3.59 (1H, m), 3.51
(3H, s), 3.27-3.17 (2H, m), 3.04-2.99 (1H, m), 2.84-2.69 (2H,
m), 2.77 (3H, s); 13C NMR δ 173.8, 173.7, 143.3, 142.9, 142.5,
140.7, 136.9, 135.6, 133.3, 132.4, 129.3, 129.1, 128.2, 127.1, 126.8,
126.4, 125.6, 125.5, 121.7, 120.8, 112.8, 81.9, 56.3, 52.3, 52.2,
40.4, 39.8, 28.8, 27.8. Because of its instability, compound 30
spontaneously collapsed to the N-demethoxymethyl derivative 30′.
Thus, full characterization data of compound 30′ is shown as
follows: colorless oil; IR 3416, 1734, 1315, 1144 cm-1; 1H NMR
δ 10.97 (1H, s), 8.83 (1H, d, J ) 8.3 Hz), 7.91-7.47 (12H, m),
7.21 (1H, t, J ) 7.6 Hz), 3.65 (3H, s), 3.61 (1H, dd, J ) 16.1, 7.3
Hz), 3.54-3.50 (1H, m), 3.50 (3H, s), 3.40 (1H, dd, J ) 16.1, 5.9
Hz), 3.18 (1H, dd, J ) 15.9, 8.5 Hz), 3.01-2.97 (1H, m), 2.92-
2.88 (1H, m); 13C NMR δ 173.72, 173.66, 142.4, 141.7, 140.6,
137.9, 136.4, 135.5, 134.0, 133.3, 130.8, 129.4, 129.3, 128.4, 127.4,
126.6, 125.6, 123.7, 123.6, 120.7, 119.2, 111.2, 52.3, 52.2, 40.5,
40.0, 28.6, 27.9; MS m/z 617 (M+, 100); HRMS calcd for C32H27O8-
NS2 617.1178, found 617.1173.
2-Ethenyl-3-ethyl-1,4-bis(phenylsulfonyl)benzene (42b): col-
1
orless oil; IR 1319, 1153, cm-1; H NMR δ 8.32 (1H, d, J ) 8.6
Hz), 8.28 (1H, d, J ) 8.6 Hz), 7.90-7.77 (4H, m), 7.67-7.44 (6H,
m), 6.64 (1H, dd, J ) 18.2, 11.9 Hz), 5.38 (1H, dd, J ) 11.9, 1.3
Hz), 4.76 (1H, dd, J ) 18.2, 1.3 Hz), 2.89, (2H, q, J ) 7.3 Hz),
0.71 (3H, t, J ) 7.3 Hz); 13C NMR δ 144.7, 144.3, 144.1, 141.7,
140.81, 140.78, 133.7, 133.5, 130.3, 129.4, 128.8, 128.7, 128.4,
127.9, 126.8, 122.7, 22.9, 13.6; FABMS m/z 413 (M++1, 100);
FABHRMS calcd for C22H21O4S2 413.0881, found 413.0892.
trans-7,8-Dimethyl-2,5-bis(phenylsulfonyl)bicyclo[4.2.0]octa-
1,3,5-triene (44b): colorless powder; mp 150.5-152 °C (CH2-
1
Cl2); IR 1323, 1157 cm-1; H NMR δ 7.92-7.90 (4H, m), 7.73
Dimethyl trans-4,9-bis(phenylsulfonyl)-5,6,7,8-tetrahydronaph-
tho[2,3-b]furan-6,7-dicarboxylate (34): colorless oil; IR 1734,
1151 cm-1; 1H NMR δ 8.09 (2H, d, J ) 7.4 Hz), 7.87-7.49 (10H,
m), 3.83-3.56 (3H, m), 3.67 (6H, s), 3.21-3.12 (2H, m), 2.95-
2.90 (1H, m); 13C NMR δ 173.7, 173.6, 150.6, 147.7, 141.4, 141.3,
135.1, 134.7, 134.0, 133.7, 133.6, 129.3, 129.1, 128.2, 128.1, 127.7,
126.9, 107.5, 52.33, 52.32, 40.2, 40.1, 27.8, 27.2; MS m/z 568 (M+,
23); HRMS calcd for C28H24O9S2 568.0862, found 568.0866.
Dimethyl trans-5,10-bis(phenylsulfinyl)-6,7,8,9-tetrahydronaph-
tho[2,3-b]pyrazine-7,8-dicarboxylate (37): the diastereoisomers
were separated by chromatography with hexane-AcOEt (1:1). Less
polar 37: yellow oil; IR 1734 cm-1; 1H NMR δ 8.99 (2H, s), 7.67-
7.65 (4H, m), 7.45-7.39 (6H, m), 3.82 (2H, dd, J ) 16.5, 8.5 Hz),
3.70 (6H, s), 3.47 (2H, dd, J ) 16.5, 5.5 Hz), 2.95-2.93 (2H, m);
13C NMR δ 173.8, 144.8, 144.1, 144.0, 142.2, 139.2, 130.4, 129.1,
124.4, 52.4, 39.8, 25.5; MS m/z 548 (M+, 79); HRMS calcd for
C28H24O6N2S2 548.1076, found 548.1079. More polar 37: yellow
(2H, s), 7.63-7.60 (2H, m), 7.55-7.52 (4H, m), 3.23 (2H, q, J )
6.9 Hz), 1.49 (6H, d, J ) 6.9 Hz); 13C NMR δ 149.8, 140.8, 140.1,
133.8, 129.4, 127.8, 127.4, 48.2, 17.5; MS m/z 412 (M+, 0.5). Anal.
Calcd for C22H20O4S2: C, 64.05; H, 4.89. Found: C, 64.13; H,
4.87.
1-Methyl-3,8-bis(phenylsulfonyl)-1,2-dihydrocyclobuta[b]naph-
thalene (46): colorless oil; IR 1321, 1145 cm-1; 1H NMR δ 8.67
(1H, dd, J ) 8.3, 1.4 Hz), 8.52 (1H, dd, J ) 8.3, 1.4 Hz), 8.06-
7.92 (2H, m), 7.60-7.24 (10H, m), 4.21-4.17 (1H, m), 3.89 (1H,
dd, J ) 16.8, 6.3 Hz), 3.28 (1H, dd, J ) 16.8, 3.6 Hz), 1.76 (3H,
d, J ) 7.1 Hz); 13C NMR δ 153.0, 146.7, 141.5, 141.3, 134.90,
134.89, 129.4, 129.3, 129.2, 129.1, 127.4, 127.3, 127.2, 127.1,
126.92, 126.90, 124.8, 124.6, 40.6, 39.7, 19.6; MS m/z 448 (M+,
100); HRMS calcd for C25H20O4S2 448.0803, found 448.0800.
2-Ethenyl-3-methyl-1,4-bis(phenylsulfonyl)naphthalene
(47): colorless oil; IR 1321, 1307, 1145 cm-1; 1H NMR δ 9.07-
8.98 (2H, m), 7.86-7.79 (2H, m), 7.60-7.24 (10H, m), 6.97 (1H,
dd, J ) 17.8, 11.4 Hz), 5.45 (1H, dd, J ) 11.4, 1.2 Hz), 4.94 (1H,
dd, J ) 17.8, 1.2 Hz), 2.71 (3H, s); 13C NMR δ 153.0, 146.7, 143.0,
142.7, 138.9, 134.2, 134.1, 129.5, 129.3, 129.2, 129.1, 127.4, 127.3,
127.2, 127.1, 126.92, 126.91, 125.4, 125.2, 120.9, 19.7; MS m/z
448 (M+, 59); HRMS calcd for C25H20O4S2 448.0803, found
448.0807.
1
oil; IR 1736 cm-1; H NMR δ 8.92 (2H, s), 7.70-7.68 (4H, m),
7.44-7.39 (6H, m), 4.30 (1H, dd, J ) 16.5, 6.1 Hz), 3.94 (1H, dd,
J ) 17.1, 7.9 Hz), 3.74 (3H, s), 3.57 (3H, s), 3.53-3.48 (1H, m),
3.31 (1H, dd, J ) 14.0, 7.9 Hz), 3.18-3.13 (1H, m), 2.99 (1H, dd,
J ) 14.0, 8.5 Hz); 13C NMR δ 173.8, 173.6, 144.8, 144.7, 144.0,
143.9, 143.2, 143.1, 142.0, 141.8, 139.3, 139.1, 130.3, 130.2,
129.04, 129.01, 124.6, 124.5, 52.5, 52.4, 40.1, 39.8, 26.0, 25.1;
MS m/z 548 (M+, 85); HRMS calcd for C28H24O6N2S2 548.1076,
found 548.1082.
Dimethyl 1-methyl-5,8-bis(phenylsulfonyl)-1,2,3,4-tetrahy-
dronaphthalene-2,3-dicarboxylate (40a): colorless oil; IR 1736,
1319, 1153 cm-1; 1H NMR δ 8.24-8.16 (2H, m), 7.88-7.82 (4H,
m), 7.67-7.52 (6H, m), 4.25-4.86 (1H, m) 3.70, 3.68, 3.61, 3.47
(total 6H, each s), 3.36-3.09 (2H, m), 2.66-2.55 (2H, m), 0.97,
0.96 (total 3H, each d, J ) 7.3 Hz); 13C NMR δ 174.4, 173.6,
173.5, 172.4, 143.9, 143,6, 143.34, 143.31, 143.2, 142.9, 140.39,
140.36, 140.2, 139.5, 139.0, 136.2, 133.9, 133.82, 133.77, 133.74,
129.40, 129.37, 129.35, 128.0, 127.93, 127.90, 127.83, 127.77,
127.67, 127.58, 127.3, 52.35, 52.25, 52.23, 52.16, 46.7, 43.8, 40.4,
Acknowledgment. This work was supported in part by a
Grant-in Aid for Scientific Research from the Ministry of
Education, Culture, Sports, Science, and Technology, Japan, for
which we are thankful.
Supporting Information Available: Experimental procedure
for the preparation of substrates 12, 17, 23, 24, 29, 33, 36, 38a,
and 45 and characterization data for compounds 11b-g, 12, 13,
15d,h, 17, 21, 22, 25, 26, 28-30, 34, 36, 37, 38a, 40a, 42a,b, and
45-47. This material is available free of charge via the Internet at
http://pubs.acs.org.
JO061014B
6914 J. Org. Chem., Vol. 71, No. 18, 2006