2,3-Bis(phenylsulfonyl)-1,3-butadiene: substrate for Michael donor/acceptors in a novel synthesis of fused cyclopentenes

Article abstract of DOI:10.1021/jo960064l

The reaction of 2,3-bis(phenylsulfonyl)-1,3-butadiene with the anion of various 1-substituted dimethyl 1-pentenedioates has been investigated with the purpose of devising a tandem conjugate addition - <3+2>-anionic cyclization route for the synthesis of bicyclo<3.3.0>octanes.The reaction proceeds with complete stereospecificity as was evidenced by treating (E)- and (Z)-dimethyl (3-cyano-2-propenyl)propanedioate with NaH in the presence of the bis(phenylsulfonyl)diene.In both cases only a single cycloadduct was obtained with no detectable signs of the other diastereomer.The overall process involves a series of three sequential conjugate additions followed by benzenesulfinate ion ejection.The success of the method is dependent on the electrophilicity of the proximal ?-bond.When 2-((5-oxo-2,5-dihydrofuranyl)methyl)malonic acid dimethyl ester was used, a mixture of the tricyclic adduct as well as an allene was obtained.In this case, elimination of the benzenesulfinate group from the initially formed sulfone-stabilized carbanion is competitive with the intramolecular <3+2>-annulation process.The base-induced reaction of dimethyl 2-(methoxycarbonyl)-2-pentenedioate with the bis(phenylsulfonyl)diene was also studied.Even though the position of the acceptor moiety on the ?-bond was altered, the tandem Michael reaction sequence still occurs.The course of the reaction is dependent upon the length of the tether as well as the relative placement of the electron-withdrawing group on the olefin.Reaction with γ-substituted β,γ-alkenyl derivatives leads to bicyclo<3.3.0> octenes, whereas β-substituted β,γ-alkenyl reagents provide bicyclo<3.3.0>octenes derived from a novel α-elimination reaction.

Full text of DOI:10.1021/jo960064l

J . Org. Chem. 1996, 61, 3829-3838
3829
2,3-Bis(p h en ylsu lfon yl)-1,3-bu ta d ien e: Su bstr a te for Mich a el
Don or /Accep tor s in a Novel Syn th esis of F u sed Cyclop en ten es
Albert Padwa,* S. Shaun Murphree, Zhijie Ni, and Scott H. Watterson
Department of Chemistry, Emory University, Atlanta, Georgia 30322
Received J anuary 9, 1996X
The reaction of 2,3-bis(phenylsulfonyl)-1,3-butadiene with the anion of various 1-substituted
dimethyl 1-pentenedioates has been investigated with the purpose of devising a tandem conjugate
addition-[3 + 2]-anionic cyclization route for the synthesis of bicyclo[3.3.0]octenes. The reaction
proceeds with complete stereospecificity as was evidenced by treating (E)- and (Z)-dimethyl (3-
cyano-2-propenyl)propanedioate with NaH in the presence of the bis(phenylsulfonyl)diene. In both
cases only a single cycloadduct was obtained with no detectable signs of the other diastereomer.
The overall process involves a series of three sequential conjugate additions followed by benzene-
sulfinate ion ejection. The success of the method is dependent on the electrophilicity of the proximal
π-bond. When 2-((5-oxo-2,5-dihydrofuranyl)methyl)malonic acid dimethyl ester was used, a mixture
of the tricyclic adduct as well as an allene was obtained. In this case, elimination of the
benzenesulfinate group from the initially formed sulfone-stabilized carbanion is competitive with
the intramolecular [3 + 2]-annulation process. The base-induced reaction of dimethyl 2-(meth-
oxycarbonyl)-2-pentenedioate with the bis(phenylsulfonyl)diene was also studied. Even though the
position of the acceptor moiety on the π-bond was altered, the tandem Michael reaction sequence
still occurs. The course of the reaction is dependent upon the length of the tether as well as the
relative placement of the electron-withdrawing group on the olefin. Reaction with γ-substituted
â,γ-alkenyl derivatives leads to bicyclo[3.3.0]octenes, whereas â-substituted â,γ-alkenyl reagents
provide bicyclo[3.3.0]octenes derived from a novel R-elimination reaction.
Functionalized five-membered carbocycles are com-
monly found in many biologically active compounds
derived from living systems.1 Ever since Comer’s struc-
ture elucidation of hirsutic acid in 1965,2 the fused
cyclopentanes have assumed a position of importance
among synthetically significant targets.3-5 As might be
expected from the frequent occurrence and biological
activity of fused cyclopentanoid natural products,1 re-
search in the area of cyclopentannulation has been brisk.
While there are many ways to classify the various
approaches, all synthetic strategies for fused cyclo-
pentenes can be divided into two broad categories: those
in which cyclization is carried out on an existing five-
membered ring6 and those in which two or more rings
are formed simultaneously.7 Over the past couple of
decades, an impressive number of effective protocols for
the synthesis of cyclopentanoids have been developed and
many of these have proven to be of value in work directed
toward the total synthesis of fused cyclopentanoid natu-
ral products.8-16
nulation processes. Indeed, there has been considerable
interest and activity in the development of single-step
[3 + 2]-ring constructions.17-43 Many such reactions have
been developed in recent years with diverse applicability
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3830 J . Org. Chem., Vol. 61, No. 11, 1996
Padwa et al.
and limitations. The attractiveness of such methodology
is enhanced by the ready availability of the two-carbon
fragments and the possibility of obtaining a broad range
of substitution on the resultant cyclopentanoids.
In connection with our program dealing with the
tandem annulation chemistry of unsaturated sulfones,44
we have been exploring the chemical reactivity of 2,3-
bis(phenylsulfonyl)-1,3-butadiene (1), a shelf-stable, highly
functionalized compound exhibiting diverse chemical
reactivity.45 We have reported preliminary results of
three sequential conjugate additions48-50 followed by
benzenesulfinate ion ejection. The tandem cyclization
sequence takes advantage of the usual role of the sulfo-
nyl group as a carbanion stabilizer51 and also illustrates
its utility as a leaving group under extremely mild
conditions.52-55
Resu lts a n d Discu ssion
We first became interested in the reaction of 2-allyl-
substituted 1,3-dicarbonyl compounds with diene 1 in
connection with the use of phenylsulfonyl-substituted
allenes of type 7 as substrates for intramolecular [2 +
2]-cycloaddition chemistry.56 The base-induced reaction
of diene 1 with a series of allyl-substituted 1,3-dicarbonyl
compounds (E ) CO2Me) proceeded by attack of the
malonate anion onto the terminal position of the diene
followed by elimination of PhSO2- to give the phenylsul-
fonyl-substituted allene 7. A subsequent thermolysis
(80-120 °C) resulted in a highly chemo- and stereose-
reactions of 1 with various bis-stabilized carbanions
which produce cyclopentenyl sulfones.46 This reaction
involves a tandem addition-proton exchange-addition
sequence. In the present paper we describe the outcome
of reactions of diene 1 with dimethyl 1-pentenedioates 5
containing electron-withdrawing substituents at the
1-position, which lead to tetrahydro-1H-pentalenes 6 in
high yield.47 The overall reaction involves a series of
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2,3-Bis(phenylsulfonyl)-1,3-butadiene
J . Org. Chem., Vol. 61, No. 11, 1996 3831
lective intramolecular [2 + 2]-cycloaddition reaction
producing cycloadduct 8. The formation of the [2 +
2]-cycloadduct was rationalized by a mechanism which
includes an initial carbon-carbon bond formation involv-
ing the central allene carbon to give a diradical inter-
mediate.56 The periselectivity observed is related to
stereoelectronic factors. Stepwise bonding prefers to
occur in a 1,6-exo manner rather than in a 1,7-endo
fashion.56 The product distribution is then determined
by the substituent pattern of the alkene and the fate of
the diradical intermediate.
To further illustrate the scope and synthetic utility of
the intramolecular [2 + 2]-process, we set out to expand
this reaction into the synthesis of other ring systems. We
found that an entirely different transformation occurred
when an electron-withdrawing substituent was situated
on the double bond. The compounds examined were
those which contained dimethyl malonate to function as
a Michael donor and a 1,2-disubstituted electron-deficient
alkene to serve as the subsequent Michael acceptor (vide
infra). These compounds (i.e., 9) react smoothly with
diene 1 under mild conditions to undergo a bicycloaddi-
tion reaction, yielding functionalized bicyclo[3.3.0]octenes
12 in good to excellent yields. For example, treatment
all, the relatively high steric demand about the carban-
ionic center present in 11 should impose a formidable
hindrance to rotation around the C-C σ-bond. Further-
more, the ejection of benzenesulfinate ion prevents ret-
rocyclization. We believe the observed facility of the ring
closure is also related to the proximity of the reacting
centers brought about by the 1,2-relationship in the rigid
five-membered ring.
As this process could be useful for the synthesis of
natural products containing fused bis(cyclopentanes),6 we
set out to probe its functional tolerance and control of
stereochemistry. Toward this end, some interesting
effects were observed upon modifying the Michael donor/
acceptor. For example, the protocol is also viable using
a reagent in which the active methine region is appended
with phenylsulfonyl groups instead of methoxycarbonyl
substituents (i.e., 13). The phenylsulfonyl groups permit
ready activation of C5 as a Michael donor and then,
following cyclization, allow for the removal of this ver-
satile functionality. In this case, a mixture of the bicyclic
compounds 14 and 15 was obtained, the latter being the
product of a facile benzenesulfinate elimination. In fact,
the tris-sulfone 14 can be readily converted to the diene
15 in 90% yield by treatment with potassium hydride.
Embedded within the skeleton of the bicyclo[3.3.0]-
octadiene 15 is an R,δ-bis(phenylsulfonyl)butadiene sub-
structure, a system which we have found to undergo a
facile methanolysis under mild conditions.56 Indeed, this
compound exhibits the same behavior; the resulting vinyl
ether 16 can then be hydrolyzed upon treatment with
acid to provide the synthetically attractive bicyclo[3.3.0]-
octenone 17 as a 2:1 mixture of diastereomers. The
exclusive regioselectivity observed in the methoxide
addition/elimination reaction can be attributed to steric
interactions which disfavor a proper trajectory to the
alternate terminus (e.g., severe 1,3-interactions with the
â-methoxycarbonyl group).
In examining further modifications to the Michael
donor/acceptor, we were curious as to whether the
incorporation of a ring in the starting material would
allow for construction of analogous tricyclic systems. We
found, as with the standard Michael process, that the
success of this method is also dependent on the electro-
philicity of the proximal π-bond. Thus, when diene 1 was
treated with furanone 18 under the standard conditions,
a mixture of allene 19 (48%) and tricyclic adduct 20 (42%)
of diene 1 with the sodium salt of malonate derivative
9b in THF at 0 °C leads to the rapid formation of 12b in
95% yield. This reaction most probably proceeds through
a sequence initiated by Michael addition onto one vinyl
sulfone moiety of the butadiene 1 to give a sulfone-
stabilized carbanion intermediate (10), which collapses
via a facile 5-exo-trig ring closure to form the presumed
second intermediate 11; a subsequent intramolecular
addition-elimination reaction provides the observed
products 12.57
An aspect of the cycloaddition worth noting is the
complete stereoselectivity of the process. For example,
subjecting isomerically pure E-alkenes 9a -c and 9e to
the tandem cyclization conditions produced only the
cyclopentane which is trans-substituted. Likewise, Z-
nitrile 9d afforded the cis-substituted cyclopentane 12d
without detectable signs of 12c. This phenomenon can
be attributed to the combination of two effects. First of
(57) Alternatively, the reaction could proceed via an SN2′ path-
way.

3832 J . Org. Chem., Vol. 61, No. 11, 1996
Padwa et al.
Sch em e 1
was obtained. In this case, elimination of the benzene-
sulfinate group from the initially formed sulfone-stabi-
lized anion is competitive with the intramolecular [3 +
2]-annulation process, apparently due to the conforma-
tional restrictions imposed by the ring system. Inasmuch
as allene formation should be a reversible process, owing
to the double-bond activation by the phenylsulfonyl
group, we theorized that the reestablishment of equilib-
rium should favor the irreversible carbocyclization.44
Indeed, treatment of 19 with sodium benzenesulfinate
induced quantitative conversion to lactone 20, thus
representing a rapid and high-yielding protocol for the
construction of such tricyclic structures. However, there
appears to be a limit to the dimensions of the cyclic ap-
pendage, as illustrated by the benzopyranone derivative
21, the sodium salt of which reacts with butadiene 1 to
form only allene 22; no trace of cyclized product is ob-
served. The extra steric bulk of the benzene ring â to
the sp2 reactive site prohibits the proper attack of the
equally demanding phenylsulfonyl-stabilized allylic anion
23. Consequently, elimination of benzenesulfinate be-
comes the only productive process. Other factors such
as electronic issues as well as the size of the ring onto
which the spiro center is formed could also be involved
here.
carried out at 0 °C (Scheme 1), simple Michael addition
onto one of the vinyl sulfone moieties is the sole reactivity
exhibited by the reagents; subsequent elimination of
benzenesulfinate gives the observed allene 26. Only at
25 °C is the reactive conformation of the intermediate
25 sufficiently populated to effect initial ring closure.
However, in this case, the constraints of the more flexible
six-membered ring fail to induce the second ring closure;
the endo-trig cyclization remains disfavored. Instead, the
intermediate anion 27 undergoes what is most likely an
internal base-promoted elimination of benzenesulfinate58
to give the alkynes 28.
We have observed thus far that (1) active methine
compounds tethered to γ-substituted â,γ-alkenyl residues
are suitable reagents for the construction of fused bicyclic
systems, (2) the steric bulk about the olefin can become
critical for the initial cyclization, and (3) analogous γ,δ-
residues induce the first cyclization to give six-membered
rings which, however, do not undergo a secondary cy-
clization. We were then curious as to what reactivity
would be exhibited by â-substituted â,γ-alkenyl reagents
under the same reaction conditions. Thus, we examined
the base-induced reactions of dimethyl 2-(methoxycar-
bonyl)-2-pentenediote (29a ) and dimethyl [2-(phenylsul-
fonyl)-2-propenyl]propanedioate (29b) with diene 1. Even
though the position of the acceptor moiety on the π-bond
has been altered, the tandem Michael reaction sequence
still occurs. The initially formed sulfonyl-stabilized 1,7-
octadienyl anion 30 is poised to undergo a plurality of
further transformations, a circumstance which is re-
flected by the fact that the product mixtures are highly
dependent upon the reaction conditions. First of all, the
steric and entropic factors associated with 30 would be
expected to work against a facile cyclization, especially
since the particularly rapid 5-exo-trig process is not an
option in this case. Thus, we were not altogether
surprised that this â-phenylsulfonyl anion also undergoes
As to other structural modifications, it should not be
surprising that the length of the tether connecting the
Michael donor and Michael acceptor moieties influences
the outcome of the reaction. Remarkably, however, such
homologous donor/acceptor reagents (i.e., 24a ,b) induced
absolutely no bis-cyclization. In fact, if the reaction is
(58) Otera, J .; Misawa, H.; Sugimoto, K. J . Org. Chem. 1986, 51,
3830.

2,3-Bis(phenylsulfonyl)-1,3-butadiene
J . Org. Chem., Vol. 61, No. 11, 1996 3833
Sch em e 2
duct 36 involves protonation followed by a subsequent
base-induced elimination. It should be noted that,
although olefin-forming reactions involving sulfinic acid
elimination of aryl sulfones are known, these reactions
are generally promoted by R-heteroatom substitution60-62
or by allylic (π)-activation of protons â to the sulfone.63-65
Clearly, â elimination of an unactivated sulfone is a
highly inefficient process requiring drastic conditions
unless the resultant double bond is conjugated with some
unsaturated group already present in the molecule.66-68
It is for this reason that we propose the alternate path
shown in the scheme which involves R-elimination of
benzenesulfinate from carbanion 34 followed by a rapid
1,2-hydrogen shift of the resulting carbene 35. Some
precedence for this rare R-elimination of an R-sulfonyl
anion can be found in an earlier report by Zimmerman
and Munch.69 The reaction of 2,2,2-triphenylethyl phenyl
sulfone (38) with a strong base was found to give
triphenylethylene (40). The reaction was suggested to
proceed by an initial R-elimination to produce carbene
39 which then underwent a 1,2-phenyl shift to afford
ethylene 40.
In conclusion, the reactions outlined herein demon-
strate the potential for using the tandem Michael addi-
tion-[3 + 2]-anionic cyclization sequence of unsaturated
sulfones in the formation of five-membered rings. The
ability to achieve high ring-juncture selectivity may find
further application in natural product synthesis. Work
is continuing in an effort to expand the scope of the
present cyclopentannulation reaction.
Exp er im en ta l Section
Melting points are uncorrected. Mass spectra were deter-
mined at an ionizing voltage of 70 eV. Unless otherwise noted,
all reactions were performed in flame-dried glassware under
an atmosphere of dry nitrogen. Solutions were evaporated
under reduced pressure with a rotary evaporator, and the
residue was chromatographed on a silica gel column using an
ethyl acetate-hexane mixture as the eluent unless specified
otherwise.
Rea ction of Dim eth yl 5-(Meth oxyca r bon yl)-2-h exen e-
d ioa t e (9a ) w it h 2,3-Bis(p h en ylsu lfon yl)-1,3-bu t a d ien e
(1). To a suspension containing 125 mg (3.1 mmol) of NaH in
20 mL of THF at 0 °C was added 0.34 mL (3.0 mmol) of
dimethyl malonate. After the solution was stirred at 0 °C for
20 min, 0.43 mL (3.1 mmol) of methyl 4-bromocrotonate was
added. The mixture was stirred at rt for 5 h, washed with a
simple benzenesulfinate elimination to some degree, thus
forming allene 31 [E ) CO2Me; SO2Ph] (Scheme 2, path
A). In addition, the allowed 6-endo-trig cyclization (path
B) produces an intermediate cyclohexyl anion (32) which,
like the analogous cyclohexylmethyl anion intermediate
27, undergoes base-promoted ejection of benzenesulfinate
to eventually form the alkynyl substituted cyclohexanes
33. However, we were quite surprised by the occurrence
of compound 36, which is obviously not derived from the
monocyclic intermediate anion 32. The structure of 36b
was assigned on the basis of its spectroscopic properties
and also by catalytic hydrogenation to bicyclo[3.3.0]-
octane 37. To account for the formation of 36, we propose
the intermediacy of the bicyclo[3.3.0]octyl anion 34, which
would arise from a tandem Michael/Michael reaction
proceeding through an initial intramolecular γ-addition
of the sulfonyl-stabilized allylic anion portion of 30 (path
C). That the cyclized carbanion 34 does not induce
elimination of the adjacent phenylsulfonyl group (as was
observed with 11) is noteworthy. The absence of this
pathway may be related to conformational restrictions
of sulfonyl carbanion 34, which cannot adopt the anti-
periplanar orientation necessary for â-elimination59 since
the three bulky substituents would be required to occupy
the same side of the five-membered ring. One conceiv-
able route by which carbanion 34 is converted to cycload-
(60) Berthon, L.; Uguen, D. Tetrahedron Lett. 1985, 26, 3975.
(61) Ley, S. V.; Lygo, B.; Wonnacott, A. Tetrahedron Lett. 1985, 26,
535.
(62) Lauron, H.; J ulia, M.; Verpeaux, J . N. J . Organomet. Chem.
1990, 387, 365.
(63) Conrad, P. C.; Fuchs, P. L. J . Am. Chem. Soc. 1978, 100, 346.
Hamann, P. R.; Fuchs, P. L. J . Org. Chem. 1983, 48, 914.
(64) Taber, D. F.; Saleh, S. A. J . Org. Chem. 1981, 46, 4817.
(65) J ones, B. A.; Varma, M.; Stirling, C. J . M. J . Am. Chem. Soc.
1986, 108, 3153.
(66) Wallace, T. J .; Hofmann, J . E.; Schriesheim, A. J . Am. Chem.
Soc. 1963, 85, 2739.
(67) Bartsch, R. A.; Bunnett, J . F. J . Am. Chem. Soc. 1969, 91,
1376.
(68) Patai, S.; Rappoport, Z.; Stirling, C. In The Chemistry of
Sulphones and Sulphoxides; Wiley: Chichester, 1988.
(69) Zimmerman, H. E.; Munch, J . H. J . Am. Chem. Soc. 1968, 90,
187.
(59) Kocienski, P. J . Chem. Ind. (London) 1981, 548.

3834 J . Org. Chem., Vol. 61, No. 11, 1996
Padwa et al.
saturated aqueous NH4Cl solution, and extracted with ether.
The organic layer was washed with water and brine and dried
over sodium sulfate. Concentration under reduced pressure
followed by flash silica gel chromatography of the residue gave
380 mg (55%) of dimethyl 5-(methoxycarbonyl)-2-hexenedioate
(9a ) as a clear oil: IR (neat) 1737, 1431, 1268, 1033, and 727
139.4, 159.7, 170.4, and 170.8. Anal. Calcd for C24H24O8S2:
C, 57.13; H, 4.80. Found: C, 56.97; H, 4.77.
Reaction of Dim eth yl (3-Cyan o-2-pr open yl)pr opan edio-
a te w ith 2,3-Bis(p h en ylsu lfon yl)-1,3-bu ta d ien e (1).
A
mixture containing 670 mg (60.0 mmol) of crotononitrile, 1.96
g (11.0 mmol) of NBS, and 10 mg of AIBN in 40 mL of CCl4
was heated at reflux for 2 h and then filtered through a pad
of Celite and washed with CCl4. Concentration of the filtrate
afforded 1-bromo-2-butenenitrile which was used in the next
step without further purification. To a solution of sodium
dimethyl malonate prepared from 1.03 mL (9.0 mmol) of
dimethyl malonate and 400 mg (9.9 mmol) of NaH in 30 mL
of THF at 0 °C was added a solution of the above bromide in
30 mL of THF. After the solution was stirred for 10 min at 0
1
cm-1; H NMR (CDCl3, 300 MHz) δ 2.79 (t, 2H, J ) 7.2 Hz),
3.51 (t, 1H, J ) 7.2 Hz), 3.70 (s, 3H), 3.74 (s, 6H), 5.98 (d, 1H,
J ) 15.6 Hz), and 6.86 (dt, 1H, J ) 15.6 and 7.2 Hz); 13C NMR
(CDCl3, 75 MHz) δ 30.9, 50.1, 51.3, 52.6, 123.3, 143.7, 166.1,
and 168.5.
To a solution containing 315 mg (1.37 mmol) of the above
triester in 10 mL of THF at 0 °C was added 71 mg (1.78 mmol)
of NaH. After the solution was stirred at 0 °C for 30 min, a
solution containing 458 mg (1.37 mmol) of 2,3-bis(phenylsul-
fonyl)-1,3-butadiene (1) in 30 mL of THF was added. The
mixture was stirred at 0 °C for 15 min, and then the reaction
was quenched with a saturated aqueous NH4Cl solution. After
removal of the solvent under reduced presure, the residue was
extracted with ether, washed with water and brine, and dried
over sodium sulfate. Flash silica gel chromatography of the
residue gave 425 mg (74%) of trans-3-(phenylsulfonyl)-2,4,6,-
6a-tetrahydro-1H-pentalene-1,5,5-tricarboxylic acid trimethyl
°C, the reaction was quenched with
a saturated NH4Cl
solution. Standard workup and purification on silica gel gave
1.01 g (57%) of a 1:1-cis,trans-mixture of dimethyl (3-cyano-
2-propenyl)propanedioate which could be separated by exten-
sive silica gel chromatography. The cis-isomer 9d exhibited
the following spectral properties: IR (neat) 2217, 1738, 1428,
1
1231, 1020, and 731 cm-1; H NMR (CDCl3, 300 MHz) δ 2.93
(td, 2H, J ) 7.2 and 1.2 Hz), 3.50 (t, 1H, J ) 7.2 Hz), 3.71 (s,
6H), 5.38 (dt, 1H, J ) 10.8 and 1.2 Hz), and 6.43-6.51 (m,
1H); 13C NMR (CDCl3, 75 MHz) δ 36.4, 49.9, 52.6, 102.1, 116.1,
150.4, and 168.2; HRMS calcd for C9H11NO4 197.0688, found
197.0692.
ester (12a ): IR (neat) 1730, 1438, 1147, 1075, and 727 cm-1
;
1H NMR (CDCl3, 300 MHz) δ 1.86 (t, 1H, J ) 13.2 Hz), 2.56
(dd, 1H, J ) 13.2 and 7.8 Hz), 2.79-2.99 (m, 3H), 3.17 (brd,
1H, J ) 21.0 Hz), 3.34 (brd, 1H, J ) 21.0 Hz), 3.38-4.44 (m,
2H), 3.56 (s, 3H), 3.65 (s, 3H), 3.67 (s, 3H), 7.47 (t, 2H, J ) 7.5
The trans-isomer 9c exhibited the following properties: IR
(neat) 2221, 1745, 1432, 1225, and 969 cm-1; 1H NMR (CDCl3,
300 MHz) δ 2.76 (td, 2H, J ) 7.2 and 1.2 Hz), 3.47 (t, 1 H, J
)7.2 Hz), 3.72 (s, 6H), 5.40 (d, 1H, J ) 16.2 Hz), and 6.57-
6.68 (m, 1H); 13C NMR (CDCl3, 75 MHz) δ 30.4, 49.9, 52.7,
102.2, 115.1, 149.5, and 168.2; HRMS calcd for C9H11NO4
197.0688, found 197.0688.
Hz), 7.56 (t, 1H, J ) 7.5 Hz), and 7.78 (d, 2H, J ) 7.5 Hz); 13
C
NMR (CDCl3, 75 MHz) δ 33.2, 37.4, 39.4, 48.9, 51.9, 52.8, 53.0,
54.7, 63.1, 127.3, 129.0, 129.1, 133.4, 139.7, 161.0, 170.7, 171.2,
and 172.4. Anal. Calcd for C20H22O8S: C, 56.86; H, 5.25.
Found: C, 56.75; H, 5.14.
To a solution containing 197 mg (1.0 mmol) of the cis-isomer
9d in 30 mL of THF was added 44 mg (1.1 mmol) of NaH at 0
°C. After the solution was stirred for 20 min, a solution of
317 mg (0.95 mmol) of 2,3-bis(phenylsulfonyl)-1,3-butadiene
(1) in 30 mL of THF was added at 0 °C. The reaction was
quenched after 20 min with a saturated NH4Cl solution,
extracted with CH2Cl2, and purified on silica gel to give 350
mg (91%) of cis-6-(phenylsulfonyl)-4-cyano-3,3a,4,5-tetrahydro-
1H-pentalene-2,2-dicarboxylic acid dimethyl ester (12d ): IR
(neat) 2243, 1730, 1659, 1438, 1268, and 1069 cm-1; 1H NMR
(CDCl3, 300 MHz) δ 2.09 (t, 1H, J ) 12.6 Hz), 2.61 (dd, 1H, J
) 13.2 and 7.8 Hz), 2.82 (d, 1H, J ) 14.7 Hz), 3.16 (d, 1H, J
) 21.0 Hz), 3.22-3.61 (m, 4H), 3.71 (s, 3H), 3.72 (s, 3H), 7.51-
7.64 (m, 3H), and 7.84 (d, 2H, J ) 7.2 Hz); 13C NMR (CDCl3,
75 MHz) δ 31.9, 33.2, 34.5, 41.4, 53.0, 53.1, 53.2, 63.4, 118.4,
127.3, 129.2, 129.3, 133.8, 139.0, 160.9, 170.0, and 171.2. Anal.
Calcd for C19H19NO6S: C, 58.60; H, 4.92; N, 3.60. Found: C,
58.45; H, 4.82; N, 3.44.
Using similar conditions, reaction of trans-9c with 2,3-bis-
(phenylsulfonyl)-1,3-butadiene (1) gave trans-6-(phenylsulfo-
nyl)-4-cyano-3,3a,4,5-tetrahydro-1H-pentalene-2,2-dicarboxy-
lic acid dimethyl ester (12c) in 89% yield: IR (neat) 2243, 1738,
1659, 1446, and 1268 cm-1; 1H NMR (CDCl3, 300 MHz) δ 1.92
(dd, 1H, J ) 13.1 and 11.4 Hz), 2.64 (dd, 1H, J ) 13.1 and 8.1
Hz), 2.84 (dd, 1H, J ) 18.9 and 9.6 Hz), 3.08 (brd, 1H, J ) 8.4
Hz), 3.18 (brd, 1H, J ) 19.6 Hz), 3.38 (brd , 1H, J ) 19.6 Hz),
3.45-3.65 (m, 2H), 3.69 (s, 3H), 3.71(s, 3H), 7.49-7.64 (m, 3H),
and 7.80 (d, 2H, J ) 7.5 Hz); 13C NMR (CDCl3, 75 MHz) δ
32.2, 33.2, 36.5, 40.9, 50.0, 53.2, 55.8, 63.0, 119.0, 127.3, 129.3,
129.6, 133.8, 139.2, 160.3, 170.2, and 170.8. Anal. Calcd for
C19H19NO6S: C, 58.60; H, 4.92; N, 3.60. Found: C, 58.37; H,
4.76; N, 3.49.
Rea ction of Dim eth yl (E)-(3-(P h en ylsu lfon yl)-2-p r o-
p en yl)p r op a n ed ioa te (9b) w ith 2,3-Bis(p h en ylsu lfon yl)-
1,3-bu ta d ien e (1). To a suspension containing 220 mg (5.5
mmol) of NaH in 60 mL of THF at rt was added 0.57 mL (5.0
mmol) of dimethyl malonate dropwise. After the solution was
stirred for 20 min, 1.30 g (5.0 mmol) of (E)-1-bromo-3-
(phenylsulfonyl)-2-propene70 was added in one portion at rt.
The reaction was quenched after 30 min with a saturated NH4-
Cl solution. The solvent was removed under reduced pressure,
and the residue was extracted with CH2Cl2. The organic layer
was washed with brine and dried over sodium sulfate. Flash
chromatography on silica gel gave 1.12 g (72%) of dimethyl
(E)-(3-(phenylsulfonyl)-2-propenyl)propanedioate (9b): IR (neat)
1
1730, 1432, 1307, 1137, and 744 cm-1; H NMR (CDCl3, 300
MHz) δ 2.79 (dt, 2H, J ) 7.4 and 1.2 Hz), 3.64 (s, 6H), 3.69 (d,
1H, J ) 7.4 Hz), 6.38 (d, 1H, J ) 15.0 Hz), 6.89 (td, 1H, J )
15.0 and 7.4 Hz), and 7.49-7.92 (m, 5H); 13C NMR (CDCl3, 75
MHz) δ 30.3, 49.8, 52.8, 127.6, 128.4, 129.2, 133.1, 133.4, 141.5,
and 168.2.
To a solution containing 312 mg (1.0 mmol) of the above
compound in 30 mL of THF was added 44 mg (1.1 mmol) of
NaH. After 20 min of stirring at rt, the solution was cooled
to 0 °C and a solution of 317 mg (0.95 mmol) of 2,3-bis-
(phenylsulfonyl)-1,3-butadiene (1) in 30 mL of THF was added.
After the solution was stirred for 10 min, the reaction was
quenched with a saturated NH4Cl solution. Removal of the
solvent under reduced pressure left a clear oil which was
extracted with CH2Cl2. The organic layer was washed with
water and brine and dried over sodium sulfate. Flash chro-
matography of the resulting residue on silica gel gave 457 mg
(95%) of trans-4,6-bis(phenylsulfonyl)-3,3a,4,5-tetrahydro-1H-
pentalene-2,2-dicarboxylic acid dimethyl ester (12b): mp 184-
Rea ction of Eth yl Meth yl 7-(Meth oxyca r bon yl)-2,4-
octa d ien ed ioa te (9e) w ith 2,3-Bis(p h en ylsu lfon yl)-1,3-
bu ta d ien e (1). A solution containing 1.4 g (10.0 mmol) of
ethyl sorbate, 1.96 g (11.0 mmol) of NBS, and 10 mg of AIBN
in 50 mL of CCl4 was heated at reflux with irradiation using
a sunlamp for 3 days. Filtration of the mixture through a pad
of Celite and purification of the residue on silica gel gave 0.80
g (30%) of ethyl 6-bromo-2,4-hexadienoate: IR (neat) 1723,
1325, 1296, and 1026 cm-1; 1H NMR (CDCl3, 300 MHz) δ 1.21
(t, 3H, J ) 7.2 Hz), 3.96 (d, 2H, J ) 7.8 Hz), 4.12 (q, 2H, J )
7.2 Hz), 5.85 (d, 1H, J ) 15.4 Hz), 6.13-6.21 (m, 1H), 6.32
185 °C; IR (KBr) 1730, 1440, 1292, 1151, 900, and 728 cm-1
;
1H NMR (CDCl3, 300 MHz) δ 1.77 (dd, 1H, J ) 13.2 and 10.8
Hz), 2.22 (dd, 1H, J ) 13.2 and 7.5 Hz), 2.91 (dd, 1H, J ) 14.7
and 7.8 Hz), 3.21 (brd, 1H, J ) 19.2 Hz), 3.29-3.35 (m, 1H),
3.43 (brd, 1H, J ) 19.2 Hz), 3.57-3.71 (m, 2H), 3.72 (s, 3H),
3.76 (s, 3H), 7.54-7.73 (m, 6H), and 7.83-7.87 (m, 4H); 13C
NMR (CDCl3, 75 MHz) δ 33.2, 36.6, 37.1, 52.4, 53.0, 53.1, 62.9,
67.9, 127.4, 128.1, 128.6, 129.4, 129.5, 133.8, 134.2, 137.6,
(70) Eisch, J . J .; Galle, J . E. J . Org. Chem. 1979, 44, 3279.

2,3-Bis(phenylsulfonyl)-1,3-butadiene
J . Org. Chem., Vol. 61, No. 11, 1996 3835
(dd, 1H, J ) 15.0 and 12.0 Hz), and 7.17 (dd, 1H, J ) 15.4
and 10.8 Hz); 13C NMR (CDCl3, 75 MHz) δ 14.0, 31.1, 60.2,
123.0, 131.6, 136.4, 142.2, and 166.1.
7.54-8.11 (m, 15H); 13C NMR (CDCl3, 75 MHz) δ 31.6, 35.1,
39.3, 49.7, 52.3, 54.6, 95.5, 127.7, 129.1, 129.4, 130.7, 131.3,
131.4, 133.8, 135.0, 135.1, 135.4, 135.6, 139.3, 157.4, and 172.1;
HRMS calcd for C22H20O6S2 (M+ - PhSO2H) 444.0701, found
444.0672.
To a solution containing sodium dimethyl malonate pre-
pared from 0.36 mL (3.2 mmol) dimethyl malonate and 153
mg (3.8 mmol) of NaH in 20 mL of THF was added a solution
of 700 mg (3.2 mmol) of the above bromide. Standard workup
and purification by silica gel chromatography gave 403 mg
(47%) of ethyl methyl 7-(methoxycarbonyl)-2,4-octadienedioate
Compound 15 exhibited the following spectral properties:
mp 153-154 °C; IR (KBr) 1730, 1440, 1305, 1145, and 1090
1
cm-1; H NMR (CDCl3, 300 MHz) δ 2.42 (ddd, 1H, J ) 17.1,
5.1 and 1.8 Hz), 2.84 (dd, 1H, J ) 16.8 and 8.1 Hz), 2.93-3.12
(m, 3H), 3.56-3.60 (m, 1H), 7.45 (s, 1H), 7.52-7.72 (m, 6H),
7.85 (d, 2H, J ) 7.2 Hz), and 7.92 (d, 2H, J ) 7.5 Hz); 13C
NMR (CDCl3, 75 MHz) δ 34.2, 39.6, 49.6, 52.2, 53.8, 127.7,
128.4, 129.4 129.6, 131.2, 133.8, 134.3, 138.0, 139.3, 159.2,
159.6, and 171.9. Anal. Calcd for C22H20O6S2: C, 59.45; H,
4.54. Found: C, 59.19; H, 4.86.
(9e): IR (neat) 1745, 1638, 1431, 1268, 1026, and 855 cm-1
;
1H NMR (CDCl3, 300 MHz) δ 1.20 (t, 3H, J ) 7.2 Hz), 2.68 (t,
2H, J ) 7.3 Hz) 3.42 (t, 1H, J ) 7.3 Hz), 3.66 (s, 3H), 3.67 (s,
3H), 4.11 (q, 2H, J ) 7.2 Hz), 5.74 (d, 1H, J ) 15.4 Hz), 5.91-
6.01 (m, 1H), 6.17 (dd, 1H, J ) 15.0 and 11.0 Hz), and 7.13
(dd, 1H, J ) 15.4 and 11.0 Hz); 13C NMR (CDCl3, 75 MHz) δ
14.1, 31.8, 40.9, 50.8, 52.3, 52.4, 60.1, 120.8, 130.8, 137.9, 143.6,
166.7, and 168.7.
A solution containing 60 mg (0.01 mmol) of 3,5,5-tris-
(phenylsulfonyl)-1,2,4,5,6,6a-hexahydropentalene-1-carboxy-
lic acid methyl ester (14) in 50 mL of THF was treated
with 20 mg (50.0 µmmol) of KH at rt for 1 h to give 48
mg (90%) of 3,5-bis(phenylsulfonyl)-1,2,6,6a-tetrahydropenta-
lene-1-carboxylic acid methyl ester (15) after workup and
purification.
To a solution of sodium ethyl methyl 7-(methoxycarbonyl)-
2,4-octadienedioate prepared from 165 mg (0.61 mmol) of 9e
and 29 mg (0.73 mmol) of NaH in 30 mL of THF at 0 °C was
added a solution of 167 mg (0.5 mmol) of 2,3-bis(phenylsulfo-
nyl)-1,3-butadiene (1) in 30 mL of THF. After the reaction
was stirred for 10 min at 0 °C, the reaction was quenched
with a saturated NH4Cl solution. Standard workup and
purification on silica gel gave 182 mg (78%) of trans-6-
(phenylsulfonyl)-4-(2-(ethoxycarbonyl)vinyl)-3,3a,4,5-tetrahy-
dro-1H-pentalene-2,2-dicarboxylic acid dimethyl ester (12e):
To a solution of 60.0 mg (0.017 mmol) of 14 in 10 mL of
methanol was added 120 mg of K2CO3. The mixture was
stirred at rt overnight. Standard workup and purification gave
23 mg (40%) of 3-(phenylsulfonyl)-5-methoxy-1,2,6,6a-tetrahy-
dropentalene-1-carboxylic acid methyl ester (16): 1H NMR
(CDCl3, 300 MHz) δ 2.39 (dd, 1H, J ) 16.2 and 5.7 Hz), 2.61
(dd, 1H, J ) 16.2 and 7.8 Hz), 2.80-3.03 (m, 3H), 3.36-3.45
(m, 1H), 3.67 (s, 3H), 3.83 (s, 3H), 5.91 (s, 1H), 7.48-7.60 (m,
3H), and 7.86 (d, 2H, J ) 7.5 Hz). This compound was easily
hydrolyzed upon standing to 3-(phenylsulfonyl)-5-oxo-1,2,3,5,-
6a-hexahydropentalene-1-carboxylic acid methyl ester (17)
in quantitative yield as an inseparable 2:1-mixture of
diastereoisomers: 1H NMR (CDCl3, 300 MHz) major isomer δ
2.24 (t, 1 H, J ) 3.3 Hz), 2.39-2.56 (m, 1H), 2.59-2.77 (m,
2H), 2.86 (dd, 1H, J ) 10.8 and 7.8 Hz), 3.21-3.33 (m, 1H),
3.75 (s, 3H), 4.42 (t, 1H, J ) 8.1 Hz), 5.73 (t, 1H, J ) 1.8 Hz),
and 7.58-7.90 (m, 5H); minor isomer δ 2.18 (t, 1H, J ) 2.7
Hz), 2.39-2.56 (m, 1H), 2.59-2.77 (m, 2H), 2.91 (dd, 1H, J )
10.8 and 7.8 Hz), 3.13-3.20 (m, 1H), 3.71 (s, 3H), 4.77(d, 1H,
J ) 9.6 Hz), 6.38 (t, 1H, J ) 1.8 Hz), and 7.58-7.90 (m, 5H).
Anal. Calcd for C16H16O5S: C, 59.99; H, 5.04. Found: C,
59.83; H, 4.96.
Rea ction of 2-((5-Oxo-2,5-d ih yd r ofu r a n -3-yl)m eth yl)-
m a lon ic Acid Dim eth yl Ester (18) w ith 2,3-Bis(p h en yl-
su lfon yl)-1,3-bu ta d ien e (1). To an ice-cold suspension con-
taining 0.27 g (6.78 mmol) of NaH in 30 mL of dry THF under
N2 was slowly added 0.65 mL (5.65 mmol) of dimethyl
malonate. The solution was stirred for 20 min at 0 °C, and
then 1.0 g (5.65 mmol) of 3-(bromomethyl)-4-hydroxy-2-
butenoic lactone71 was slowly added via syringe. The solution
was allowed to warm to rt over 30 min, and the reaction
was then quenched by the addition of a saturated NH4Cl
solution. The reaction mixture was extracted with CH2Cl2,
and the organic layer was collected, washed with water, and
dried over anhydrous NaSO4. Concentration under reduced
pressure afforded a crude yellow oil which was subjected to
silica gel chromatography to give 0.68 g (53%) of 18 as a clear
oil: IR (neat) 1766, 1730, 1439, 1303, and 1147 cm-1; 1H NMR
(CDCl3, 300 MHz) δ 2.95 (d, 2H, J ) 7.4Hz), 3.68 (t, 1H, J )
7.4 Hz), 3.71 (s, 6H), 4.73 (s, 2H), and 5.82 (s, 1H); 13C NMR
(CDCl3, 75 MHz) δ 27.4, 49.5, 53.0, 73.1, 116.8, 166.0, 168.2,
and 173.2.
IR (neat) 1730, 1652, 1439, 1154, and 1069 cm-1 1H NMR
;
(CDCl3, 300 MHz) δ 1.25 (t, 3H, J ) 7.2 Hz), 1.87 (t, 1H, J )
13.0 Hz), 2.54 (dd, 1H, J ) 13.0 and 7.8 Hz), 2.73-2.85 (m,
2H), 3.12-3.20 (m, 1H), 3.26 (brd, 1H, J ) 20.1 Hz), 3.41 (brd,
1H, J ) 20.1 Hz), 3.69-3.79 (m, 1H), 3.74 (s, 3H), 3.75 (s, 3H),
4.15 (q, 2H, J ) 7.2 Hz), 5.77 (d, 1H, J ) 15.6 Hz), 6.87 (dd,
1H, J ) 15.6 and 6.6 Hz), 7.52-7.64 (m, 3H), and 7.86 (d, 2H,
J ) 7.2 Hz); 13C NMR (CDCl3, 75 MHz) δ 14.1, 33.7, 37.0, 42.0,
49.2, 53.0, 53.2, 57.0, 60.5, 63.6, 122.2, 127.5, 127.9, 129.3,
129.9, 133.5, 140.0, 147.1, 162.2, 166.0, 170.9, and 171.5. Anal.
Calcd for C23H26O8S: C, 59.72; H, 5.67. Found: C, 59.63; H,
5.42.
R ea ct ion of Met h yl 5,5-Bis(p h en ylsu lfon yl)-2-p en -
ten oa te (13) w ith 2,3-Bis(p h en ylsu lfon yl)-1,3-bu ta d ien e
(1). To a suspension containing 380 mg (9.6 mmol) of NaH in
100 mL of THF was added 2.36 g (8.0 mmol) of bis(phenyl-
sulfonyl)methane in several portions. The mixture was heated
at reflux for 2 h and cooled to 0 °C. To this mixture was added
1.34 mL (8.8 mmol) of 4-bromocrotonate in 100 mL of THF.
The mixture was stirred at rt for 2 days, and the reaction
was then quenched with a saturated NH4Cl solution. Removal
of THF under reduced pressure was followed by extraction
with CH2Cl2, washing with water and brine, and drying over
sodium sulfate. The resulting residue was purified by silica
gel flash chromatography to give 1.36 g (43%) of methyl 5,5-
bis(phenylsulfonyl)-2-pentenoate (13): mp 147-148 °C; IR
1
(KBr) 1708, 1655, 1305, 1165, 1085, and 740 cm-1; H NMR
(CDCl3, 300 MHz) δ 3.07 (t, 2H, J ) 6.3 Hz), 3.70 (s, 3H), 4.52
(t, 2H, J ) 6.3 Hz), 5.77 (d, 1H, J ) 15.6 Hz), 6.74-6.84 (m,
1H), and 7.56-7.98 (m, 10H); 13C NMR (CDCl3, 75 MHz) δ
28.0, 51.4, 81.7, 124.0, 129.0, 129.3, 134.6, 137.3, 141.6, and
165.6.
To a suspension containing 38 mg (0.95 mmol) of KH in 15
mL of THF at 0 °C was added 230 mg (0.58 mmol) of 13 in
one portion. The mixture was stirred at rt for 45 min. To the
above mixture was added a solution of 195 mg (0.58 mmol) of
2,3-bis(phenylsulfonyl)-1,3-butadiene (1) in 15 mL of THF.
After the solution was stirred for 1 h at 0 °C, the reaction was
quenched with a NH4Cl solution. Standard workup and
purification on silica gel gave 91 mg (27%) of 3,5,5-tris-
(phenylsulfonyl)-1,2,4,5,6,6a-hexahydropentalene-1-carboxy-
lic acid methyl ester (14) and 80 mg (31%) of 3,5-bis-
(phenylsulfonyl)-1,2,6,6a-tetrahydropentalene-1-carboxylic acid
methyl ester (15). Compound 14 exhibited the following
spectral properties: IR (KBr) 1732, 1442, 1305, 1135, and 720
cm-1; 1H NMR (CDCl3, 300 MHz) δ 2.36 (dd, 1H, J ) 15.1 and
10.2 Hz), 2.76-2.86 (m, 3H), 2.91 (dd, 1H, J ) 15.1 and 9.0
Hz), 2.99-3.08 (m, 1H), 3.38 (dd, 1H, J ) 18.0 and 1.8 Hz),
3.55-3.65 (m, 1H), 3.66 (s, 3H), 4.05 (d, 1H, J ) 19.8 Hz), and
A 0.32 g (1.40 mmol) sample of 18 was slowly added into a
stirred ice-cold suspension containing 73 mg (1.83 mmol) of
NaH in 25 mL of dry THF under N2. The solution was stirred
for 20 min at 0 °C, and then 0.51 g (1.54 mmol) of 2,3-bis-
(phenylsulfonyl)-1,3-butadiene (1) in 15 mL of dry THF was
slowly added. The solution was allowed to warm to rt over 30
min, and the reaction was then quenched with a saturated
NH4Cl solution. The reaction mixture was extracted with CH2-
Cl2, and the organic layer was collected, washed with water,
(71) Boeckman, R. H.; Ho, S. S. J . Am. Chem. Soc. 1982, 104,
1033.

3836 J . Org. Chem., Vol. 61, No. 11, 1996
Padwa et al.
and dried over anhydrous NaSO4. Concentration of the
mixture under reduced pressure afforded a crude yellow
residue which was subjected to silica gel chromatography to
give 0.24 g (41%) of 5-(phenylsulfonyl)-3-oxo-3,3a,4,6-tetrahy-
dro-2-oxacyclopenta[c]pentalene-7,7-dicarboxylic acid dimethyl
ester (20) as a clear oil: IR (neat) 1766, 1730, 1432, 1168, 1019,
dimethyl (E)-6-(methoxycarbonyl)-2-heptenedioate (24a )72 in
30 mL of THF was added 44 mg (1.1 mmol) of NaH at 0 °C.
After the solution was stirred for 20 min, a solution containing
317 mg (0.95 mmol) of 2,3-bis(phenylsulfonyl)-1,3-butadiene
(1) in 30 mL of THF was added. After the solution was stirred
for 10 min, the reaction was quenched by the addition of a
saturated NH4Cl solution. Standard workup and purification
gave 334 mg (81%) of dimethyl 6-[2-(phenylsulfonyl)-2,3-
butadienyl]-6-(methoxycarbonyl)-2-heptenedioate (26a ): IR
1
and 884 cm-1; H NMR (benzene-d6) δ 1.73 (d, 1H, J ) 13.6
Hz), 2.07 (d, 1H, J ) 13.6 Hz), 2.29 (d, 1H, J ) 4.3 Hz), 2.74-
2.84 (m, 1H), 2.90-2.98 (m, 1H), 3.11-3.23 (m, 1H), 3.20 (s,
6H), 3.63 (d, 1H, J ) 9.9 Hz), 3.70 (d, 1H, J ) 9.9 Hz), 4.03 (d,
1H, J ) 17.7 Hz), 7.09-7.11 (m, 3H), and 7.98-8.01 (m, 2H);
13C NMR (CDCl3, 75 MHz) δ 32.2, 40.2, 40.9, 44.4, 53.4, 53.5,
60.3, 64.6, 76.4, 127.8, 129.5, 132.5, 134.1, 139.3, 158.4, 170.7,
171.6, and 177.2. Anal. Calcd for C20H20O8S: C, 57.13; H,
4.80. Found: C, 57.05; H, 4.68.
1
(neat) 1958, 1730, 1652, 1197, 1069 and 855 cm-1; H NMR
(CDCl3, 300 MHz) δ 1.91 (brs, 4H), 2.80 (brs, 2H), 3.52 (s, 6H),
3.58 (s, 3H), 5.24 (brs, 2H), 5.64 (d, 1H, J ) 15.6 Hz), 6.05-
6.71 (m, 1H), 7.40-7.53 (m, 3H), and 7.75 (d, 2H, J ) 7.5 Hz);
13C NMR (CDCl3, 75 MHz) δ 26.5, 28.3, 29.7, 51.1, 52.4, 56.0,
85.2, 104.7, 108.4, 121.3, 127.8, 128.9, 133.5, 139.4, 147.0,
166.3, 169.8, and 207.9; HRMS Calcd for C21H24O8S 436.1192,
found 436.1179.
In addition to compound 20, 0.28 g (48%) of 2-[2-(phenyl-
sulfonyl)buta-2,3-dienyl]-2-((5-oxo-2,5-dihydrofuran-3-yl)-
methyl)malonic acid dimethyl ester (19) was also isolated
from the chromatographic separation: IR (neat) 1958, 1930,
1745, 1723, 1147, and 1026 cm-1; 1H NMR (CDCl3, 300 MHz)
δ 2.97 (t, 2H, J ) 2.5 Hz), 3.05 (s, 2H), 3.68 (s, 6H), 4.71 (s,
2H), 5.37 (t, 2H, J ) 2.5 Hz), 5.75 (s, 1H), 7.55 (t, 2H, J ) 7.5
The reaction of 24a with diene 1 was also carried out at 25
°C. To a solution of 500 mg (2.05 mmol) of 24a in 30 mL of
THF at 0 °C was added 90 mg (2.25 mmol) of NaH. After 20
min of stirring, the mixture was warmed to rt, and a solution
of 634 mg (1.9 mmol) of 2,3-bis(phenylsulfonyl)-1,3-butadiene
(1) in 50 mL of THF was added. The mixture was stirred for
an additional 10 min, and the reaction was quenched by the
addition of a saturated NH4Cl solution. Standard workup and
purification gave 627 mg (76%) of 3-ethynyl-4-((methoxycar-
bonyl)methyl)-3-(phenylsulfonyl)cyclohexane-1,1-dicarboxy-
lic acid dimethyl ester (28a ) as an inseparable 1:1 mixture of
Hz), 7.66 (t, 1H, J ) 7.5 Hz), and 7.83 (d, 2H, J ) 7.5 Hz); 13
C
NMR (CDCl3, 75 MHz) δ 29.9, 31.5, 53.1, 56.5, 73.9, 85.7,
108.3, 118.3, 128.1, 129.3, 134.0, 139.3, 164.6, 169.3, 173.2,
and 208.3; HRMS Calcd for C20H20O8S: 420.0878, found
420.0878.
cis,trans-isomers: IR (KBr) 2111, 1723, 1439, and 1303 cm-1
;
A mixture containing 87 mg (0.21 mmol) of 19, 41 mg (0.31
mmol) of K2CO3, and 2 mg (0.01 mmol) of sodium benzene-
sulfinate in 20 mL of dry THF under nitrogen was stirred at
rt for 36 h. The solution was filtered through a pad of Celite
and concentrated to give 5-(phenylsulfonyl)-3-oxo-3,3a,4,6-
tetrahydro-2-oxacyclopenta[c]pentalene-7,7-dicarboxylic acid
dimethyl ester (20) in quantitative yield.
1H NMR (CDCl3, 300 MHz) δ 1.37 (dt, 1H, J ) 13.2 and 4.8Hz),
1.64-1.86 (m, 4H), 2.20-2.84 (m, 4H), 3.30 (dd, 1H, J ) 15.6
and 1.5 Hz), 3.49 (s, 3H), 3.53 (s, 3H), 3.61 (s, 3H), 3.65 (s,
6H), 3.68 (s, 3H), 7.48-7.70 (m, 6H), and 7.90-7.95 (m, 4H);
13C NMR (CDCl3, 75 MHz) δ 24.1, 24.3, 26.6, 29.5, 29.6, 31.8,
35.5, 36.1, 36.5, 36.7, 51.6, 51.7, 52.0, 52.2, 52.6, 53.0, 53.1,
64.8, 65.3, 76.4, 79.2, 79.5, 80.2, 128.4, 128.8, 130.6, 130.9,
134.2, 134.4, 134.9, 135.1, 169.6, 169.9, 171.0, 171.2, 171.8,
and 172.2. Anal. Calcd for C21H24O8S: C, 57.78; H, 5.55.
Found: C, 57.62; H, 5.58.
Rea ction of 4-[2,2-Bis(m eth oxyca r bon yl)eth yl]-7-m eth -
oxycou m a r in (21) w ith 2,3-Bis(p h en ylsu lfon yl)-1,3-bu ta -
d ien e (1). To a suspension containing 163 mg (4.08 mmol) of
NaH in 30 mL of THF was added dimethyl malonate drop-
wise. The mixture was stirred for 20 min at rt and was
then added to a solution of 1.0 g (3.72 mmol) of 4-(bromo-
methyl)-7-methoxycoumarin in 150 mL of THF at rt. The
solution was stirred at rt for 20 min, and the reaction was
quenched by the addition of a NH4Cl solution. Standard
workup and purification gave 870 mg (73%) of 4-(2,2-bis-
(methoxycarbonyl)ethyl)-7-methoxycoumarin (21): IR (KBr)
Rea ction of Dim eth yl (E)-[4-(P h en ylsu lfon yl)-3-bu te-
n yl]p r op a n ed ioa t e (24b ) w it h 2,3-Bis(p h en ylsu lfon yl)-
1,3-bu ta d ien e (1). To a solution of 2.55 g (8.7 mmol) of
diethyl ((phenylsulfonyl)methyl)phosphonate73 in 100 mL of
THF at 0 °C was added 384 mg (9.6 mmol) of NaH. The
mixture was stirred at rt for 30 min. To above solution was
added 1.63 g (8.7 mmol) of 2-(3-oxopropyl)malonic acid di-
methyl ester72 in 50 mL of THF. The reaction was heated at
reflux for 4 h. Standard workup and purification gave 1.45 g
(51%) of dimethyl (E)-[4-(phenylsulfonyl)-3-butenyl]propanedio-
ate (24b): IR (neat) 1730, 1439, 1311, and 1147 cm-1; 1H NMR
(CDCl3, 300 MHz) δ 1.99 (q, 2H, J ) 7.8 Hz), 2.24, (dt, 2H, J
) 7.8 and 6.9 Hz), 3.29 (t, 1H, J ) 7.5 Hz), 3.64 (s, 6H), 6.30
(d, 1H, J ) 15.3 Hz), 6.86 (dt, 1H, J ) 15.3 and 6.9 Hz), 7.44-
7.58 (m, 3H), and 7.79 (d, 2H, J ) 7.2 Hz); 13C NMR (CDCl3,
75 MHz) δ 26.4, 28.7, 50.4, 50.5, 127.4, 129.1, 131.4, 133.2,
140.2, 144.5 and 168.9.
To a solution of 326 mg (1.0 mmol) of 24b in 30 mL of THF
at 0 °C was added 48 mg (1.2 mmol) of NaH. After the solution
was stirred for 10 min, a solution of 317 mg (0.95 mmol) of
2,3-bis(phenylsulfonyl)-1,3-butadiene (1) in 30 mL of THF was
added. The mixture was stirred for 10 min at 0 °C, and the
reaction was quenched by the addition of a solution of NH4Cl.
Standard workup and purification gave 321 mg (65%) of 2-(2-
(phenylsulfonyl)buta-2,3-dienyl)-2-(4-(phenylsulfonyl)but-3-
enyl)malonic acid dimethyl ester (26b): IR (neat) 1958, 1730,
1439, and 1140 cm-1; 1H NMR (CDCl3, 300 MHz) δ 1.91-2.05
(m, 4H), 2.84 (t, 2H, J ) 2.7 Hz), 3.58 (s, 6H), 5.25 (t, 2H, J )
2.7 Hz), 6.24 (d, 1H, J ) 15.0 Hz), 6.78 (td, 1H, J ) 15.0 and
6.0 Hz), 7.44-7.56 (m, 6H), and 7.76-7.81 (m, 4H); 13C NMR
(CDCl3, 75 MHz) δ 26.0, 28.5, 29.4, 52.6, 56.1, 85.4, 108.5,
127.5, 128.1, 129.1, 129.2, 131.0, 133.2, 13.8, 139.4, 140.3,
144.8, 169.8 and 208.0. Anal. Calcd for C25H26O8S2: C, 57.90;
H, 5.06. Found: C, 57.78; H, 4.89.
1
2954, 1730, 1701, 1289, and 827 cm-1; H NMR (CDCl3, 300
MHz) δ 3.36 (d, 2H, J ) 7.5 Hz), 3.76 (s, 6H), 3.77 (t, 1H, J )
7.5 Hz), 3.87 (s, 3H), 6.11 (s, 1H), 6.82-6.89 (m, 2H), and 7.54
(d, 1H, J ) 9.0 Hz); 13C NMR (CDCl3, 75 MHz) δ 30.2, 50.0,
53.0, 55.7, 101.1, 111.6, 111.9, 112.4, 124.9, 151.8, 155.4, 160.6,
162.7, and 168.3.
To a solution of 200 mg (0.62 mmol) of 21 in 50 mL of THF
was added 28 mg (0.68 mmol) of NaH. The solution was
stirred at rt for 30 min and then cooled to 0 °C. To the
above mixture was added a solution of 187 mg (0.56 mmol)
of 2,3-bis(phenylsulfonyl)-1,3-butadiene (1) in 30 mL of
THF. After the solution was stirred for 10 min, the reac-
tion was quenched by the addition of a saturated NH4Cl
solution. Standard workup and purification gave 165 mg
(57%) of 4-[2,2-bis(methoxycarbonyl)-4-(phenylsulfonyl)-4,5-
hexadienyl]-7-methoxylcoumarin (22): IR (KBr) 1930, 1609,
1282, and 1140 cm-1 1H NMR (CDCl3, 300 MHz) δ 2.96 (t,
;
2H, J ) 3.0 Hz), 3.35 (s, 2H), 3.49 (s, 6H), 3.80 (s, 3H), 5.40 (t,
2H, J ) 3.0 Hz), 6.00 (s, 1H), 6.71-6.77 (m, 2H), 7.38 (d, 1H,
J ) 9.0 Hz), 7.46-7.60 (m, 3H), and 7.80 (d, 2H, J ) 7.2 Hz);
13C NMR (CDCl3, 75 MHz) δ 29.6, 32.4, 52.7, 55.6, 56.5, 86.0,
101.0, 108.7, 111.9, 112.6, 113.2, 125.2, 127.9, 129.1, 133.7,
139.3, 150.3, 155.1, 160.1, 162.5, 169.1, and 207.8. Anal.
Calcd for C26H24O9S: C, 60.92; H, 4.72. Found: C, 60.75; H,
4.58.
Rea ction of Dim eth yl (E)-6-(Meth oxyca r bon yl)-2-h ep -
ten ed ioa te (24a ) w ith 2,3-Bis(p h en ylsu lfon yl)-1,3-bu ta -
d ien e (1). To a solution containing 244 mg (1.0 mmol) of
(72) Bunce, R. A.; Pierce, J . D. Synth. Commun. 1987, 19, 67.
(73) Shahak, I.; Almog, J . Synthesis 1970, 145.

2,3-Bis(phenylsulfonyl)-1,3-butadiene
J . Org. Chem., Vol. 61, No. 11, 1996 3837
The reaction of 24b with diene 1 was also carried out at 25
°C. To a solution containing 163 mg (0.5 mmol) of dimethyl
(E)-[4-(phenylsulfonyl)-3-butenyl]propanedioate (24b) in 30 mL
of THF at rt was added 30 mg (0.75 mmol) of NaH. After the
solution was stirred for 10 min, a solution of 160 mg (0.48
mmol) of 2,3-bis(phenylsulfonyl)-1,3-butadiene (1) in 30 mL
of THF was added. The solution was stirred at rt for 10 min,
and the reaction was quenched by the addition of a NH4Cl
solution. Standard workup and purification gave 183 mg
(72%) of 3-ethynyl-3-(phenylsulfonyl)-4-((phenylsulfonyl)-
methyl)cyclohexane-1,1-dicarboxylic acid dimethyl ester (28b)
as a 3:1-mixture of diastereoisomers. The major isomer
showed the following properties: mp 186-187 °C; IR (KBr)
2108, 1730, 1439, 1311, and 1140 cm-1; 1H NMR (CDCl3, 300
MHz) δ 1.40 (td, 1H, J ) 13.5 and 3.9 Hz); 1.92 (qd, 1H,
J ) 13.5 and 3.3 Hz), 2.23 (dd, 1H, J ) 13.5 and 2.1 Hz),
2.34 (d, 1H, J ) 13.5 Hz), 2.43 (brd, 1H, J ) 13.5 Hz), 2.60 (s,
1H), 2.62-2.74 (m, 2H), 3.26 (dd, 1H, J ) 14.4 and 9.9 Hz),
3.55 (s, 3H), 3.64 (s, 3H), 4.58 (d, 1H, J ) 14.4 Hz), and 7.52-
7.98 (m, 10H); 13C NMR (CDCl3, 75 MHz) δ 26.9, 29.5, 35.0,
36.4, 52.2, 52.3, 57.8, 64.6, 76.1, 79.8, 128.2, 129.0, 129.3, 130.9,
133.8, 134.6, 134.6, 134.7, 139.6, 169.5, and 170.9. Anal.
Calcd for C25H26O8S2: C, 57.90; H, 5.06. Found: C, 57.82; H,
4.95.
2H, J ) 3.8 Hz), 5.47 (s, 1H), 6.14 (s, 1H), 7.54 (t, 2H, J ) 7.5
Hz), 7.64 (t, 1H, J ) 7.5 Hz), and 7.88 (d, 2H, J ) 7.5 Hz); 13
C
NMR (75 MHz, CDCl3) δ 28.6, 33.4, 52.0, 52.6, 56.2, 86.1,
109.3, 127.9, 128.2, 129.1, 129.6, 133.6, 135.1, 139.9, 166.9,
and 169.84. Anal. Calcd for C20H22O8S: C, 56.86; H, 5.25.
Found: C, 56.78; H, 5.22.
Rea ction of Dim eth yl [2-(P h en ylsu lfon yl)-2-p r op en yl]-
p r op a n ed ioa te (29b) w ith 2,3-Bis(p h en ylsu lfon yl)-1,3-
bu ta d ien e (1). To a mixture of 240 mg (5.0 mmol) of NaH in
30 mL of THF at 0 °C was added 0.57 mL (5.0 mmol) of
dimethyl malonate. After the solution was stirred for 10 min
at 0 °C, a solution of 2,3-bis(phenylsulfonyl)-1-propene (1) in
30 mL of THF was added. The solution was stirred at 0 °C
for 10 min, and the reaction was quenched with a saturated
NH4Cl solution. Standard workup and purification on silica
gel gave 0.97 g (62%) of dimethyl [2-(phenylsulfonyl)-2-pro-
penyl]propanedioate (29b): IR (neat) 1735, 1434, 1302, 1079,
1
and 747 cm-1; H NMR (CDCl3, 300 MHz) δ 2.79 (d, 2H, J )
7.5 Hz), 3.64 (s, 6H), 3.78 (t, 1H, J ) 7.5 Hz), 5.80 (s, 1H),
6.37 (s, 1H), 7.51 (t, 2H, J ) 7.5 Hz), 7.61 (t, 1H, J ) 7.5 Hz),
and 7.83 (d, 2H, J ) 7.5 Hz); 13C NMR (CDCl3, 75 MHz) δ
28.9, 50.1, 52.7, 126.6, 128.2, 129.3, 133.7, 138.3, 146.7, and
168.3.
To a solution of 156 mg (0.5 mmol) of 29b in 15 mL of THF
at 0 °C was added 24 mg (0.6 mmol) of NaH. After the solution
was stirred for 10 min, a solution of 159 mg (0.48 mmol) of
2,3-bis(phenylsulfonyl)-1,3-butadiene (1) in 15 mL of THF was
added. After 10 min, the mixture was quenched by the
addition of a saturated NH4Cl solution. Standard workup
followed by silica gel chromatographic separation and purifica-
tion gave 75 mg (35%) of 2-[2-(phenylsulfonyl)allyl]-2-[2-
(phenylsulfonyl)buta-2,3-dienyl]malonic acid dimethyl ester
(31b), 73 mg (30%) of 3-ethynyl-3,5-bis(phenylsulfonyl)cyclo-
hexane-1,1-dicarboxylic acid dimethyl ester (33b), and 75 mg
(35%) of 3a,6a-bis(phenylsulfonyl)-3,3a,4,6a-tetrahydro-1H-
pentalene-2,2-dicarboxylic acid dimethyl ester (36b). Compond
31b showed the following properties: IR (neat) 2256, 1960,
1736, 1440, and 1152 cm-1; 1H NMR (300 MHz, CDCl3) δ 2.96
(s, 2H), 2.99 (t, 2H, J ) 3.4 Hz), 3.65 (s, 6H), 5.29 (t, 2H, J )
3.4 Hz), 5.74 (s, 1H), 5.34 (s, 1H), and 7.53-7.88 (m, 10H);13C
NMR (75 MHz, CDCl3) δ 28.8, 30.8, 53, 55.9, 86.1, 108.8, 127.0,
128.2, 128.3, 129.2, 129.3, 133.7, 133.8, 138.5, 139.6, 145.6,
169.2, and 207.7. Anal. Calcd for C24H24O8S2: C, 57.13; H,
4.80. Found: C, 56.83; H, 4.69.
The minor isomer was a viscous oil which exhibited the
following properties: IR (KBr) 2108, 1730, 1446, 1303, and
1140 cm-1 1H NMR (CDCl3, 300 MHz) δ 1.77 (dt, 1H, J )
;
13.8 and 3.6 Hz), 2.25-2.53 (m, 4H), 2.59 (brd, 1H, J ) 14.4
Hz), 2.66 (d, 1H, J ) 14.4 Hz), 2.98 (brd, 1H, J ) 11.4 Hz),
3.38 (dd, 1H, J ) 11.7 and 11.4 Hz), 3.52 (s, 3H), 3.72 (s, 3H),
4.19 (brd, 1H, J ) 14.4 Hz), 7.49-7.68 (m, 6H), 7.89 (d, 2H, J
) 7.8 Hz), and 7.95 (d, 2H, J ) 7.5 Hz). Anal. Calcd for
C
25H26O8S2: C, 57.90; H, 5.06. Found: C, 57.71; H, 5.04.
Rea ction of 2-(Meth oxylca r bon yl)-4-m eth ylen ep en -
ta n ed ioic Acid Dim eth yl Ester (29a ) w ith 2,3-Bis(p h en -
ylsu lfon yl)-1,3-bu ta d ien e (1). To a suspension containing
0.12 g (2.90 mmol) of NaH in 50 mL of THF was slowly added
0.26 mL (2.23 mmol) of dimethyl malonate. The solution was
stirred for 15 min, and then 0.27 mL (2.23 mmol) of methyl
2-(bromomethyl)acrylate was slowly added. After the solution
was stirred for 30 min at rt, the reaction was quenched by the
addition of a saturated solution of NH4Cl. Workup and
purification gave 460 mg (89%) of 29a : IR (neat) 1730, 1631,
1439, 1232, and 1147 cm-1 1H NMR (300 MHz, CDCl3) δ
;
2.84 (d, 2H, J ) 7.5 Hz), 3.66 (s, 6H), 3.69 (t, 1H, J ) 7.5 Hz),
3.70 (s, 3H), and 5.60 (s, 1H), and 6.16 (s, 1H); 13C NMR (75
MHz, CDCl3) δ 31.4, 50.6, 51.9, 52.5, 128.0, 136.3, 166.6, and
169.
Compound 33b showed the following properties: mp 162-
163 °C; IR (KBr) 2256, 1731, 1437, and 897 cm-1 1H NMR
;
(CDCl3, 300 MHz) δ 1.77 (t, 1H, J ) 12.9 Hz), 2.05 (dd, 1H, J
) 15.3 and 13.2 Hz), 2.48 (s, 1H), 2.49 (brd, 1H, J ) 15.3 Hz),
2.63 (d, 1H, J ) 16.2 Hz), 2.86 (brd, 1H, J ) 13.2 Hz), 3.37 (d,
1H, J ) 16.2 Hz), 3.70 (s, 3H), 3.75 (s, 3H), 4.04 (tt, 1H, J )
12.9 and 3.3 Hz), 7.42 (t, 2H, J ) 7.8 Hz), 7.60-7.76 (m, 6H),
and 7.92 (d, 2H, J ) 7.5 Hz); 13C NMR (CDCl3, 75 MHz) δ
28.2, 30.4 33.0, 52.2, 53.0, 53.4, 54.8, 60.0, 81.1, 128.5, 128.7,
129.4, 131.0, 133.6, 134.1, 134.4, 136.8, 169.0, and 170.4. Anal.
Calcd for C24H24O8S2: C, 57.13; H, 4.80. Found: C, 57.21; H,
4.76.
A solution of 0.38 g (1.67 mmol) of 29a in 10 mL of THF
was slowly added to an ice-cold suspension containing 0.09 g
(2.17 mmol) of NaH in 20 mL of THF. The reaction mixture
was stirred for 15 min at 0 °C, and then 0.56 g (1.67 mmol) of
2,3-bis(phenylsulfonyl)-1,3-butadiene (1) in 10 mL of THF was
slowly added. After the solution was stirred for 15 min at 0
°C, the reaction was quenched by the addition of a saturated
solution of NH4Cl. Standard workup and purification gave
0.30 g (43%) of 6a-(phenylsulfonyl)-4,6a-dihydro-1H-pentalene-
2,2,3a-tricarboxylic acid trimethyl ester (36a ): IR 1730, 1446,
Compound 36b showed the following properties: mp 228-
1
229 °C; IR (KBr) 1739, 1437, 1304, and 1143 cm-1; H NMR
1
1254, and 1147 cm-1; H NMR (300 MHz, CDCl3) δ 2.34 (dd,
(CDCl3, 300 MHz) δ 2.12 (d, 1H, J ) 15.9 Hz), 2.21 (dd, 1H, J
) 15.9 and 2.7 Hz), 2.83 (d, 1H, J ) 13.8 Hz), 3.47 (brd, 1H,
J ) 15.9 Hz), 3.52 (s, 3H), 3.53 (d, 1H, J ) 15.9 Hz), 3.46 (d,
1H, J ) 13.8 Hz), 3.78 (s, 3H), 5.30 (dd, 1H, J ) 5.7 and 1.8
Hz), 5.95 (t, 1H, J ) 2.4 Hz), 7.48-7.64 (m, 6H), 7.94 (d, 2H,
J ) 7.5 Hz), and 8.00 (d, 2H, J ) 7.5 Hz); 13C NMR (CDCl3, 75
MHz) δ 39.8, 42.9, 44.9, 53.2, 53.4, 57.4, 79.8, 87.7, 128.6,
128.9, 130.3, 130.5, 131.4, 133.9, 135.4, 138.1, 138.5, 169.8 and
1H, J ) 17.4 and 2.5 Hz), 2.42 (d, 1H, J ) 14.3 Hz), 2.79 (d,
1H, J ) 14.3 Hz), 3.04 (dt, 1H, J ) 17.4 and 2.1 Hz), 3.23 (d,
1H, J ) 14.3 Hz), 3.54 (d, 1H, J ) 14.3 Hz), 3.63 (s, 3H), 3.76
(s, 3H), 3.79 (s, 3H), 5.19 (dd, 1H, J ) 5.4 and 2.5 Hz), 5.87
(dt, 1H, J ) 5.4 and 2.1 Hz), 7.49 (t, 2H, J ) 7.5 Hz), 7.62 (t,
1H, J ) 7.5 Hz), and 7.80 (d, 2H, J ) 7.5 Hz); 13C NMR (75
MHz, CDCl3) δ 39.0, 42.2, 46.9, 52.4, 53.0, 53.1, 58.8, 61.4,
88.0, 128.4, 129.5, 129.9, 133.7, 137.3, 137.7, 170.5, 171.3, and
172.4. Anal. Calcd for C20H22O8S: C, 56.86; H, 5.25. Found:
C, 56.63; H, 5.14.
170.7. Anal. Calcd for
Found: C, 56.62; H, 4.79.
C24H24O8S2: C, 57.13; H, 4.80.
A mixture of 47 mg (0.09 mmol) of 36b and 20 mg of PtO2
in 30 mL of acetic acid and 30 mL of ethyl acetate under H2
(70 psi) was hydrogenated overnight. Removal of the solvent
and purification on silica gel gave 42 mg (87%) of 3a,6a-bis-
(phenylsulfonyl)hexahydropentalene-2,2-dicarboxylic acid di-
In addition to compound 36a , 0.34 g (48%) of 2-[2-(phenyl-
sulfonyl)buta-2,3-dienyl]-2-(methoxycarbonyl)-4-methylene-
pentanedioic acid dimethyl ester (31a ) was also isolated from
the chromatographic separation as a clear oil: IR 1960, 1730,
1632, and 1304 cm-1
2H, J ) 3.8 Hz), 3.01 (s, 2H), 3.61 (s, 6H), 3.68 (s, 3H), 5.42 (t,
;
1H NMR (300 MHz, CDCl3) δ 2.84 (t,
methyl ester (37): IR (KBr) 1730, 1439, 1303, and 1133 cm-1
;
1H NMR (CDCl3, 300 MHz) δ 1.80-1.90 (m, 3H), 2.10-2.25

3838 J . Org. Chem., Vol. 61, No. 11, 1996
Padwa et al.
(m, 1H), 2.39 (d, 2H, J ) 15.0 Hz), 2.67-2.75 (m, 2H), 3.60 (d,
2H, J ) 15.0 Hz), 3.64 (s, 3H), 3.90 (s, 3H), 7.53-7.65 (m, 6H),
and 8.02 (d, 4H, J ) 7.2 Hz); 13C NMR (CDCl3, 75 MHz) δ
20.2, 34.5, 42.0, 53.7, 58.1, 77.2, 82.3, 128.9, 130.6, 133.8, 138.7,
170.5, and 172.3. Anal. Calcd for C24H26O8S2: C, 56.90; H,
5.18. Found: C, 56.71; H, 5.09.
used in these studies was made possible through equip-
ment grants from the NIH and NSF.
Su p p or t in g In for m a t ion Ava ila b le: 1H NMR and 13C
NMR spectra for new compounds lacking analyses (8 pages).
This material is contained in libraries on microfiche, im-
mediately follows this article in the microfilm version of the
journal, and can be ordered from the ACS; see any current
masthead page for ordering information.
Ack n ow led gm en t. We gratefully acknowledge sup-
port of this work by the National Institutes of Health
(CA-26750). Use of the high-field NMR spectrometer
J O960064L