Stereoselective synthesis of racemic and optically active E-vinyl and E- dienyl sulfoxides via Wittig reaction of α-sulfinyl phosphonium ylides

Article abstract of DOI:10.1021/jo981100e

A series of α-sulfinyl phosphonium ylides have been obtained in the reaction of phosphonium mono- and diylides with sulfinic acid esters. The use of (-)-(S)-menthyl p-toluenesulfinate in this reaction afforded the corresponding (S)-((p-tolylsulfinyl)methyl)triphenylphosphonium ylide. The Wittig reaction of these ylides with saturated and unsaturated aldehydes resulted in the formation of racemic and optically active (+)-(R)-vinyl and dienyl sulfoxides with the E-geometry. The synthesis of (+)-(R)-((p- tolylsulfinyl)methyl)triphenylphosphonium iodide as a precursor of the optically active ylide has also been described.

Full text of DOI:10.1021/jo981100e

9716
J . Org. Chem. 1998, 63, 9716-9722
Ster eoselective Syn th esis of Ra cem ic a n d Op tica lly Active E-Vin yl
a n d E-Dien yl Su lfoxid es via Wittig Rea ction of r-Su lfin yl
P h osp h on iu m Ylid es
Marian Mikołajczyk,*,† Wiesława Perlikowska,† J an Omelan´czuk,† Henri-J ean Cristau,‡ and
Anne Perraud-Darcy‡
Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Department of Organic
Sulfur Compounds, 90-363 Ło´dz´, Sienkiewicza 112, Poland, and Laboratoire de Chimie Organique
ENSC, 8 rue de l’Ecole Normale, F-34053 Montpellier, Cedex, France
Received J une 9, 1998
A series of R-sulfinyl phosphonium ylides have been obtained in the reaction of phosphonium mono-
and diylides with sulfinic acid esters. The use of (-)-(S)-menthyl p-toluenesulfinate in this reaction
afforded the corresponding (S)-((p-tolylsulfinyl)methyl)triphenylphosphonium ylide. The Wittig
reaction of these ylides with saturated and unsaturated aldehydes resulted in the formation of
racemic and optically active (+)-(R)-vinyl and dienyl sulfoxides with the E-geometry. The synthesis
of (+)-(R)-((p-tolylsulfinyl)methyl)triphenylphosphonium iodide as a precursor of the optically active
ylide has also been described.
In tr od u ction
method requires the synthesis of vinylic organometallic
reagents of desired geometry while the Horner-Wittig
reaction is nonstereoselective and usually affords mix-
tures of E- and Z-isomeric vinyl sulfoxides (Scheme 1).6,7
Optically pure E- and Z-R,â-unsaturated sulfoxides can
be prepared by stereoselective reduction of chiral 1-alky-
nyl sulfoxides, which, in turn, are synthesized from (-)-
(S)-menthyl p-toluenesulfinate and alkynylmagnesium
bromides (Scheme 2).8,9
In the hope that the Wittig reaction will occur in a
stereoselective way, we turned our attention to R-sulfinyl
phosphorus ylides. Surprisingly, before our studies this
class of compounds was practically unknown and their
reactivity unexplored. In 1968 Hamid and Trippett10
isolated R-sulfinyl ylide 1a from the reaction between
phenyl sulfine and the corresponding phosphorus ylide.
In the American patent11 from 1972 three other R-sulfinyl
phosphorus ylides 1b-d stabilized by an ester or cyano
group were reported. They were prepared by condensa-
tion of phosphorus ylides with sulfinyl chlorides in the
presence of triethylamine. More recently, Aitken et al.12
used the latter method to obtain a series of R-sulfinyl
R-phenyl triphenylphosphonium ylides for their vacuum
pyrolysis studies. However, both reactions shown in
Scheme 3 do not allow the synthesis of optically active
(at sulfur) R-sulfinyl ylides 1.
R,â-Unsaturated sulfoxides are valuable intermediates
in a variety of synthetic transformations and useful
building blocks in the synthesis of biologically active
compounds.1 Vinyl sulfoxides display three main types
of reactivity. Thus, they undergo electrophilic addition
to the carbon-carbon double bond, are Michael acceptors
in addition of carbon and heteroatom nucleophiles, and
serve as dienophiles in the Diels-Alder reaction. More-
over, it is also possible to generate R-lithiated vinyl
sulfoxides and use them as nucleophilic reagents. Re-
cently, the use of chiral, enantiomerically pure vinyl
sulfoxides in asymmetric synthesis has received increas-
ing attention.2,3
The general methods of the synthesis of optically active
R,â-unsaturated sulfoxides are based on the Andersen
reaction of (-)-(S)-menthyl p-toluenesulfinate with vi-
nylic Grignard reagents4 and the Horner-Wittig reaction
of (+)-(S)-dimethoxyphosphorylmethyl p-tolyl sulfoxide
with carbonyl compounds developed in our laboratory.5
However, the efficient, stereoselective synthesis of arbi-
trarily substituted vinyl sulfoxides with defined E- or
Z-geometry is still faced with difficulties. The first
* To whom correspondence should be addressed. Tel.: (48-42)681-
58-32. Fax: (48-42)684-71-26. E-mail: marmikol@bilbo.cbmm.lodz.pl.
† Polish Academy of Sciences.
‡ Ecole Normale.
(6) For a recent review on R-phosphoryl sulfoxides see: Mikołajczyk,
M.; Bałczewski, P. In Advances in Sulfur Chemistry; Block, E., Ed.;
J AI Press Inc.: Greenwich, CT, 1994; Vol. 1, pp 41-96.
(7) Similarly, the Craig’s one-pot modification of the Horner-Wittig
reaction results in various ratios of geometrical isomers of R,â-
unsaturated sulfoxides: Craig, D.; Daniels, K.; McKenzie, A. R.
Tetrahedron 1993, 49, 11263-11304.
(8) Kosugi, H.; Kitaoka, M.; Tagami, K.; Takahashi, A.; Uda, H. J .
Org. Chem. 1987, 58, 1078-1082.
(9) Interestingly, Z-vinyl sulfoxides can be transformed into their
E-isomers without racemization at sulfur via lithiation and protona-
tion: Fawcett, J .; House, S.; J enkins, P. R.; Lawrance, N. J .; Russell,
D. R. J . Chem. Soc., Perkin Trans. 1 1993, 67-73.
(10) Hamid, A. M.; Trippett, S. J . Chem. Soc. C 1968, 1612-1615.
(11) J osey, A. D. U.S. Pat 3,647,856; Chem. Abstr. 1972, 76, 141023r.
(12) (a) Aitken, R. A.; Drysdale, M. J .; Ryan, B. M. J . Chem. Soc.,
Chem. Commun. 1993, 1699-1700. (b) Aitken, R. A.; Drysdale, M. J .;
Ferguson, G.; Lough, A. J . J . Chem. Soc., Perkin Trans. 1 1998, 875-
880.
(1) (a) Drabowicz, J .; Kiełbasin´ski, P.; Mikołajczyk, M. in The
Synthesis of Sulphones and Sulphoxides and Cyclic Sulphides; Patai,
S., Rappoport, Z., Stirling, C. J . M., Eds.; J ohn Wiley and Sons: New
York, 1994; pp 109-388. (b) Posner, G. H. The Chemistry of Sulphones
and Sulphoxides; Patai, S., Rappoport, Z., Stirling, C. J . M., Eds.; J ohn
Wiley and Sons: New York, 1988; pp 823-849. (c) Oae, S.; Uchidea,
Y. Ibid., pp 583-664.
(2) (a) Carren˜o, M. C. Chem. Rev. 1995, 95, 1717-1760. (b) Aversa,
M. C.; Barattucci, A.; Bonaccorsi, P.; Giannetto, P. Tetrahedron:
Asymmetry, 1997, 8, 1339-1367.
(3) Mikołajczyk, M.; Drabowicz, J .; Kiełbasin´ski, P.; Chiral Sulfur
Reagents: Applications in Asymmetric and Stereoselective Synthesis;
CRC Press: Boca Raton, New York, 1997.
(4) (a) Abbott, D. J .; Colonna, S.; Stirling, C. J . M. J . Chem. Soc. D
1971, 472-473; J . Chem. Soc., Perkin Trans 1 1976, 492-498. (b)
Posner, G. H.; Tang, P. W. J . Org. Chem. 1978, 43, 4131-4136.
(5) Mikołajczyk, M.; Midura, W. H.; Grzejszczak, S.; Zatorski, A.;
Chefczyn´ska, A. J . Org. Chem. 1978, 43, 473-478.
10.1021/jo981100e CCC: $15.00 © 1998 American Chemical Society
Published on Web 12/01/1998

E-Vinyl and E-Dienyl Sulfoxides
J . Org. Chem., Vol. 63, No. 26, 1998 9717
Sch em e 1
Sch em e 4
Sch em e 2
Ta ble 1. Ra cem ic r,â-Un sa tu r a ted Su lfoxid es 8,
R1S(O)CHdCHR2, P r ep a r ed by Wittig Rea ction w ith
r-Su lfin yl P h osp h on iu m Ylid e 6a
Sch em e 3
no.
R1
R2
solvent
E/Z (%)a
yield (%)b,c
8a
p-Tol Ph
THF
C6H6
C6H6
C6H6
C6H6
C6H6
C6H6
C6H6
C6H6
68/32
97/3
99/1
100/0
96/4
100/0
100/0
100/0
100/0
84
88
78
85
70
50
62
65
66
8b
8c
8d
8e
8f
p-Tol p-ClPh
p-Tol p-MeOPh
p-Tol o-MePh
p-Tol p-NO2Ph
p-Tol Et
8g
8h
p-Tol i-Pr
p-Tol E-MeCHdCH
a
Determined by 1H NMR analysis of the crude reaction mixture.
After column chromatography. c Calculated on 0.5 equiv of the
b
In this paper we wish to report a new general synthesis
of racemic and enantiopure R-sulfinyl phosphorus ylides
and their stereoselective reaction with carbonyl com-
pounds leading to vinyl and dienyl sulfoxides of E-
geometry.
phosphonium iodide 2.
and fully or almost fully E-stereoselective, especially
when benzene is used as a solvent. The E-geometry of
the double bond in 8 was unambiguously confirmed by
observing characteristic coupling patterns of the R-ole-
finic proton signals (doublets) and J values (ca. 15.5 Hz)
(eq 1).
Resu lts a n d Discu ssion
On e-P ot Syn th esis of Ra cem ic E-Vin yl a n d E-
Dien yl Su lfoxid es fr om R-Su lfin yl P h osp h on iu m
Ylid es. To establish the stereochemistry of the Wittig
reaction of R-sulfinyl phosphonium ylides and to develop
a new synthesis of the latter, in the first part of this work
the desired R-sulfinyl phosphonium ylide 6a was obtained
by treatment of methyltriphenylphosphonium ylide (3)
(generated from methyltriphenylphosphonium iodide (2)
and n-BuLi) with racemic methyl p-toluenesulfinate (4a )
in a benzene solution.
Due to a fast proton transfer from the primarily formed
R-sulfinyl methyltriphenylphosphonium salt 5a to the
ylide 3 regenerating the starting phosphonium salt 2, the
reaction was carried out using a 0.5 equiv amount of the
sulfinate 4a with respect to 3. The ylide 6a so generated
(Scheme 4) was then treated with aldehydes 7a -h at
room temperature, and the reaction mixture was refluxed
for ca. 10 h in benzene or THF. The usual workup gave
the crude sulfoxides 8a -h which, after determination of
Interestingly, 1-(p-tolylsulfinyl)-2-(p-nitrophenyl)ethene
(8e) obtained according to the procedure described above
as the E-isomer turned out to be configurationaly un-
stable. Its purification by column chromatography on
silica gel with CH2Cl2 as eluent was accompanied by
isomerization affording a mixture of E-8e and Z-8e in a
82:18 ratio. This ratio was unchanged when the pure,
solid sulfoxide 8e was stored in the dark. When, however,
the sulfoxide 8e was kept in a CH2Cl2 solution in the
presence of silica gel for a longer time, the isomerization
1
the E/Z ratio by H NMR spectroscopy, were purified by
column chromatography. The yields and E:Z ratios of the
sulfoxides 8 are listed in Table 1.
It was gratifying to find that the synthesis of vinyl and
dienyl sulfoxides 8 via the Wittig reaction is very efficient

9718 J . Org. Chem., Vol. 63, No. 26, 1998
Mikołajczyk et al.
Ta ble 2. Op tica lly Active Su lfoxid es E-(R)-8, TolS(O)CHdCHR, P r ep a r ed by Wittig Rea ction w ith (S)-r-Su lfin yl
P h osp h on iu m Ylid e 6a
[R]D (solvent)
no.
R
present work
lit. data
ee (%)
yield (%)
8a
8c
8h
Ph
p-MeOPh
E-MeCHdCH
+159.5 (CHCl3)
+100.0 (CHCl3)
+287.5 (acetone)
+158.5 (CHCl3)
+389.7 (EtOH)
+283.4 (CHCl3)
+166.0 (CHCl3)5
100a
96
100
87
82
61
+224.5 (Acetone)17
8i
8j
H
+413 (EtOH)8
94
100
40
20
CH2dCH
+283.8 (CHCl3)18
a
Contains 1.4% of Z-isomer. This value was calculated based on the known rotations values of E- and Z-isomers of 8a equal to [R]D
)
+172.92 (CHCl3) and [R]D ) -766.67 (CHCl3), respectively.
Sch em e 5
the S-configuration was assigned to the ylide 6a . Con-
sequently, the reaction of (-)-(S)-menthyl sulfinate 4b
with the ylide 3 should occur with inversion of configu-
ration at sulfur, as depicted in Scheme 5.
A comparison of the optical rotation values of the
sulfoxides E-(+)-(R)-8 obtained in the present work with
those reported in the literature and claimed to correspond
to enantiopure forms (see Table 2) showed that only in
the case of 8j optical rotations were the same. A big
difference in rotation values was noted for the sulfoxide
8h , our value being much higher. Therefore, it was
prudent to determine enantiomeric purity of 8 by an
independent and accurate method. We decided to apply
the NMR method and use (-)-(S)-tert-butylphenylphos-
phinothioic acid (9), t-BuPhP(S)OH, as an excellent chiral
solvating agent,16 especially for sulfoxides.16a In the case
1
of the racemic sulfoxide (()-E-8a , the H NMR spectrum
of the diastereomeric solvates formed with (-)-(S)-9
exhibited clearly resolvable R-vinyl proton doublets at δ
) 6.91 and δ ) 6.89 ppm (∆δ ) 4.9 Hz), while the
spectrum of the sample of E-8a , [R]D ) +159.5, in the
presence of this acid exhibited only one doublet at δ )
6.89 ppm. This indicated that our reaction product was
enantiomerically pure. Its smaller rotation value than
that reported by us earlier5 is most probably due to
minute amounts (1.4%) of the Z-isomer of 8a which has
much larger rotation value and opposite in sign (Z-8a ,
[R]D ) -766.75). In a similar way, the enantiomeric purity
of the unknown sulfoxide E-8c was determined as 96%
[(∆δH(C1) ) 4.9 Hz for a mixture of (()-E-8c and (-)-(S)-
9]. The racemic sulfoxide E-8i, when mixed with (-)-(S)-
9, formed diastereomeric solvates which showed in the
1H NMR spectrum different chemical shifts for each
vinylic proton (three double doublets). Interestingly, the
∆δ value for cis- and trans-protons at C2 was also
different and equal to 2.5 and 5.1 Hz, respectively. The
1H NMR spectrum of a mixture of the sulfoxide E-8i, [R]D
) +389.7, and (-)-(S)-9 allowed one to determine its
enantiomeric purity as 94% and to confirm that the
sulfoxide E-8b, [R]D ) +413, obtained by Kosugi et al.8
was enantiopure. Finally, the 1H NMR spectra of the
racemic and enantiopure sulfoxide E-8h in the presence
of (-)-(S)-9 (see Figure 1) showing well-resolved doublets
of the R-vinyl proton (∆δ ) 3.2 Hz) confirmed a full
enantiomeric purity of the dienyl sulfoxide E-8h prepared
herein by the Wittig reaction.
was slowly occurring and resulting after 30 days in the
formation of a mixture of E-8e and Z-8e in a 30:70 ratio.
Syn th esis of Op tica lly Active E-Vin yl a n d E-
Dien yl Su lfoxid es fr om (S)-((p -Tolylsu lfin yl)m eth -
yl)tr ip h en ylp h osp h on iu m Ylid e. In contrast to sulfi-
nyl chlorides and achiral sulfines, sulfinic esters are
optically stable compounds and easily available as pure
enantiomers or diastereomers.13 Therefore, the present
approach to the synthesis of R-sulfinyl phosphorus ylides
1 makes it possible to prepare them in an enantioselec-
tive way from optically active sulfinates. As in the case
of (+)-(S)-dimethoxyphosphorylmethyl p-tolyl sulfoxide,5
the optically active title ylide 6a was prepared from (-)-
(S)-menthyl p-toluenesulfinate (4b)14sa common sub-
strate in the synthesis of optically active sulfinyl
derivativessupon treatment with the ylide 3 (Scheme 5).
Then, the ylide 6a was reacted in situ with saturated
and unsaturated aldehydes 7 to afford optically active
sulfoxides E-8. For the synthesis of the sulfoxide 8i
trimer of formaldehyde was used. The results of this one-
pot, enantioselective synthesis of 8 are summarized in
Table 2.
1
It deserves to be noted that in all cases the H NMR
spectra of the crude, optically active sulfoxides 8 did not
reveal the presence of the corresponding Z-isomers. Since
vinyl and dienyl sulfoxides E-8 formed were dextrorota-
tory, the R-chirality at sulfur was assigned to all of
them.15 Moreover, taking into account the fact that the
Wittig reaction does not disturb configuration at sulfur,
(15) For a relationship between the chirality at sulfur, E,Z-geometry,
and sign of optical rotation in R,â-unsaturated sulfoxides, see: Mikoła-
jczyk, M.; Midura, W. H.; Wladislaw, B.; Biaggio, F. C.; Marzorati, L.
Tetrahedron 1997, 53, 2959-2972.
(16) (a) Drabowicz, J .; Dudzin´ski, B.; Mikołajczyk, M.; Tetrahe-
dron: Asymmetry 1992, 3, 1231-1232. (b) Omelan´czuk, J .; Mikołajc-
zyk, M.; Tetrahedron: Asymmetry 1996, 7, 2687-2694. (c) Drabowicz,
J .; Dudzin´ski, B.; Mikołajczyk, M.; Colonna, S.; Gaggero, N. Tetrahe-
dron: Asymmetry 1997, 8, 2267-2270.
(13) Mikołajczyk, M.; Drabowicz, J . Top. Stereochem. 1982, 13, 333-
468.
(14) Solladie, G. Synthesis 1981, 185-196. (-)-(S)-menthyl p-
toluenesulfinate (4b) was obtained from (-)-(1R,2S,5R)-menthol.

E-Vinyl and E-Dienyl Sulfoxides
J . Org. Chem., Vol. 63, No. 26, 1998 9719
as revealed by the 1H NMR spectra (R-vinyl protons
3
appeared at δ ) 6.43 and 6.21 ppm with J ) 14.7 and
9.7 Hz, respectively). Column chromatography afforded
the enantiomerically pure sulfoxide (1E,3E)-(+)-(R)-8k
with the same rotation values as the literature ones ([R]D
) +225.1 (acetone);17 [R]D ) +168.9 (CHCl3)18) (eq 3).
However, the Wittig reaction with the racemic or
optically acitve salt 5a carried out under phase-transfer
catalytic conditions gave less satisfactory results in terms
of E-stereoselectivity and optical purity. Thus, treatment
of (()-5a with benzaldehyde under classical PTC condi-
tions (see eq 4) resulted in the formation of 8a as a
F igu r e 1. 1H NMR (300 MHz) spectra (R-dienyl proton region)
of the racemic (a) and enantiopure (b) sulfoxide E-8h in the
presence of (-)-(S)-tert-butylphenylphosphinothioic acid (9).
Having established the E-stereochemistry and enan-
tioselectivity of the Wittig reaction of the optically active,
R-sulfinyl ylide 6a , we next focused our attention on
isolation and characterization of the R-sulfinyl phospho-
nium salt 5a in the hope that it may be the best starting
reagent for the synthesis of optically active R,â-unsatur-
ated sulfoxides. It was found that, when the reaction of
the ylide 3 with the sulfinate (-)-(S)-4b was carried out
in THF and the reaction mixture neutralized with
hydroiodic acid, two phosphonium iodides 5a and 2 were
formed (eq 2). Fortunately, the latter turned out to be
mixture of E and Z isomers in comparable amounts. On
the other hand, the sulfoxide (+)-(R)-8i obtained from
the reaction of (+)-(S)-5a with formaldehyde (40% water
solution) was only 81% optically pure (eq 5).
Syn th esis of Ra cem ic a n d Op tica lly Active r,â-
Un satu r ated Su lfoxides fr om Su lfin ates an d Lith iu m
Dim eth yld ip h en ylp h osp h on iu m Diylid e.19 Although
the synthesis of the R-sulfinyl phosphonium ylide 6a and
R-sulfinyl phosphonium iodide 5a has been accomplished
as shown in Scheme 4 and eq 2, this method has one
drawback connected with the formation of the ylide 6a
together with the starting phosphonium salt 2. This is
due to intermolecular proton transfer from 5a to 3. To
overcome this problem, it is advantageous to use instead
of the monoylide 3 dimethyldiphenylphosphonium diylide
(11),20 which may be easily generated from the corre-
sponding phosphonium salt 10 and 2 equiv of BuLi. As
(17) Solladie, G.; Ruiz, P.; Colobert, F.; Carren˜o, M. C.; Garcia-
Ruano, J . L. Synthesis 1991, 1011-1012.
insoluble in THF and was removed simply by filtration.
Evaporation of the solvent and column chromatography
afforded the desired, analytically pure R-sulfinyl phos-
phonium salt (+)-5a in 70% yield.
When the salt (+)-(S)-5a was used for the Wittig
reaction with trans-cinnamaldehyde (7k ), the corre-
sponding dienyl sulfoxide 8k was formed as a mixture of
two geometrical isomers 1E, 3E and 1Z, 3E in a 98:2 ratio
(18) (a) Paley, R. S.; de Dios, A.; Fernandez de la Pradilla, R. F.
Tetrahedron Lett. 1993, 34, 2429-2432. (b) Paley, R. S.; de Dios, A.;
Estroff, L. A.; Lafontaine, J . A.; Montero, C.; McCullcy, D. J .; Rubio,
M. B.; Ventura, M. P.; Weers, H. L.; Fernandez de la Pradilla, R. F.;
Castro, S.; Dorado, R.; Morente, M. J . Org. Chem. 1997, 62, 6326-
6343.
(19) A part of this work has been published in a preliminary form:
Mikołajczyk, M.; Perlikowska, W.; Omelan´czuk, J .; Cristau, H.-J .;
Perraud-Dercy, A. Synlett 1991, 913-915.
(20) Cristau, H.-J . Chem. Rev. 1994, 94, 1299-1313.

9720 J . Org. Chem., Vol. 63, No. 26, 1998
Mikołajczyk et al.
Sch em e 6
Sch em e 7
Sch em e 8
Ta ble 3. Ra cem ic r,â-Un sa tu r a ted Su lfoxid es 8,
R1S(O)CHdCHR2, P r ep a r ed by Wittig Rea ction w ith
r-Su lfin yl P h osp h on iu m Ylid es 12
no.
R1
R2
solvent
E/Z (%)a
yield (%)b
8l
Me
Et
n-Pr
i-Pr
t-Bu
Ph
Ph
Ph
Ph
Ph
Ph
Ph
THF
THF
THF
THF
THF
THF
91/9
100/0
100/0
100/0
100/0
96/4
78
70
71
75
48
69
8m
8n
8o
8p
8r
a
Determined by 1H NMR analysis of the crude reaction mixture.
b
After column chromatography.
expected, the diylide 11 reacted with methyl sulfinates
4c-h used in equimolar amounts to give (R-sulfinylm-
ethyl)diphenylmethylphosphonium ylides 12 as the only
reaction products. In this case, the primarily formed
ylides 12′ were transformed into more stable ylides 12
via intramolecular proton migration. Subsequent reaction
of the latter with benzaldehyde 7a resulted in the
formation of vinyl sulfoxides 8l-r in high yields (over
70%) and with full or almost full E-stereoselectivity
(Scheme 6, Table 3). A lower yield (48%) was only noted
for tert-butyl styryl sulfoxide (8p ), which under the
reaction conditions (reflux in THF for 20h) underwent
partial decomposition.
When (-)-(S)-menthyl sulfinate 4b was reacted with
the diylide 11, the corresponding optically active R-sulfi-
nyl ylide 12a was generated with inversion of configu-
ration at the sulfur atom. The in situ reaction of this ylide
with carbonyl compounds produced optically active vinyl
sulfoxides. The results with benzaldehyde 7a and form-
aldehyde 7i are shown in Scheme 7.
egy was applied. On the basis of the literature data21,22
we were able to obtain in 53% yield diphenylphos-
phinylmethyl p-tolyl sulfoxide (14) from the reaction of
the methyl p-tolyl sulfoxide carbanion with diphenyl-
chlorophosphine. It should be noted that we used phe-
nyllithium and not LDA for deprotonation of sulfoxide
which resulted in a more efficient and cleaner condensa-
tion. For characterization purposes, 14 was converted
into the corresponding phosphine sulfide 15 by addition
of elemental sulfur. Methylation of 14 with freshly
distilled methyl iodide afforded the desired phosphonium
salt 13a as a crystalline substance, mp 104-106 °C. Its
Wittig reaction with benzaldehyde 7a gave the sulfoxide
8a which was a 95:5 mixture of E- and Z-isomers,
respectively (Scheme 8).
Con clu sion s
In summary, a new method for the synthesis of E-vinyl
and E-dienyl sulfoxides has been developed which is
It was also of interest to prepare (R-sulfinylmethyl)-
diphenylmethylphosphonium iodide (13a ), which could
serve as a substrate for the Wittig reaction under differ-
ent experimental conditions. Unfortunately, our attempt
to quench the ylide 12a with hydroiodic acid and isolate
the salt 13a was unsuccessful. Therefore, another strat-
(21) Vedejs, E.; Mastalerz, H.; Meier, G. P.; Powell, D. W. J . Org.
Chem. 1981, 46, 5253-5254.
(22) Alcock, N. W.; Brown, J . M.; Evans, P. L. Organomet. Chem.
1988, 356, 233-247.

E-Vinyl and E-Dienyl Sulfoxides
J . Org. Chem., Vol. 63, No. 26, 1998 9721
1-(p-Tolylsu lfin yl)-2-(p-m eth oxyph en yl)eth en e (8c): Mp
based on the Wittig reaction of R-sulfinyl phosphonium
ylides. The latter, practically unknown class of phospho-
nium ylides, have been obtained from phosphonium
monoylides or diylides upon treatment with sulfinic acid
esters. This approach is particularly attractive as the use
of (-)-(S)-menthyl p-toluenesulfinate allowed one to
synthesize in an enantioselective way optically active (S)-
R-sulfinyl phosphonium ylides and use them for the
preparation of (+)-(R)-vinyl and -dienyl sulfoxides of
E-geometry. In addition, (+)-(R)-((p-tolylsulfinyl)methyl)-
triphenylphosphonium iodide as a suitable precursor of
the corresponding ylide has been obtained and character-
ized. This study has also demonstrated that enantiomeric
tert-butylphenylphosphinothioic acids may be used as
efficient chiral solvating agents for determination of
enantiomeric excesses of vinyl and dienyl sulfoxides.
1
81-82 °C; H NMR (CDCl3) δ 2.39 (s, 3H), 3.80 (s, 3H), 6.67
[d, J AB ) 15.5 Hz (E)], 6.87-7.67 (m, 9H). Anal. Calcd for
C
16H16O2S; C, 70.56; H, 5.92; S, 11.77. Found: C, 70.32; H,
6.00; S, 11.64.
1-(p-Tolylsu lfin yl)-2-(o-m eth ylp h en yl)eth en e (8d ): Col-
1
orless oil; H NMR (CDCl3) δ 2.41 (s, 3H), 2.45 (s, 3H), 6.52
and 6.73 [2d, J AB ) 10.3 Hz (Z), J AB ) 15.4 Hz (E), 1H], 7.14-
7.66 (m, 9H). Anal. Calcd for C16H16OS: C, 74.96; H, 6.29; S,
12.51. Found: C, 75.08; H, 6.26; S, 12.42.
1-(p-Tolylsu lfin yl)-2-(p-n itr op h en yl)eth en e (8e) (E:Z/
82:18): Mp 141-143 °C; 1H NMR (CDCl3) δ 2.42 (s, 3H), 6.64
and 6.99 [2d, J AB ) 10.7 Hz (Z), J AB ) 15.4 Hz (E), 1H], 7.12
and 7.21-8.22 [d, J AB ) 10.7 Hz (Z), and m, 9H]. Anal. Calcd
for C15H13O3SN: C, 62.70; H, 4.56; S, 11.16. Found: C, 62.52;
H, 4.68; S, 11.02.
1
1-(p-Tolylsu lfin yl)-1-bu ten e (8f): Colorless oil; H NMR
(CDCl3) δ 1.03 (t, 3H, J ) 7.4 Hz), 2.19-2.23 (m, 2H), 2.37 (s,
3H); 6.18 (dt, J AB ) 15.2 Hz, J AB ) 1.6 Hz, 1H), 6.61 (dt, J AB
) 15.2 Hz, J ) 6.2 Hz, 1H), 7.28-7.50 (m, 4H). Anal. Calcd
for C11H14OS: C, 68.00; H, 7.26; S, 16.50. Found: C, 68.20; H,
7.10; S, 16.40.
1-(p-Tolylsu lfin yl)-4-m eth yl-1-bu ten e (8g): Colorless oil;
1H NMR (CDCl3) δ 1.05 (d, 6H, J ) 6.8 Hz), 2.39 (s, 3H) 2.42-
2.54 (m, 1H), 6.14 (dd, J AB ) 15.3 Hz J ) 1.4 Hz, 1H), 6.55
(dd, J AB ) 15.3 Hz, J ) 6.3 Hz, 1H), 7.25-7.52 (m, 4H).8
(1E,3E)-1-(p-Tolylsu lfin yl)-1,3-p en ta d ien e (8h ): Mp 59-
60 °C; 1H NMR (CDCl3) (300 MHz) δ 1.80 (d, 3H, J ) 5.3 Hz),
2.37 (s, 3H) 6.06-6.10 (m, 2H), 6.18 (d, 1H, J ) 15.1 Hz), 6.88-
6.96 (m, 1H), 7.26-7.51 (m, 4H). (Lit. 17).
Op tica lly Active r,â-Un sa tu r a ted Su lfoxid es 8a ,c,h -
k . (E)-(+)-(R)-1-(p-Tolylsu lfin yl)-2-p h en yleth en e (8a ): Mp
82 °C, [R]D ) +159.5° (c, 2.11, CHCl3); 1H NMR (CDCl3) δ 2.41
(s, 3H), 6.81 (d, 1H, J AB ) 15.5 Hz) 7.30-7.60 (m, 10H).5
(E)-(+)-(R)-1-(p -Tolylsu lfin yl)-2-(p -m et h oxyp h en yl)-
eth en e (8c): Mp 94-95 °C, [R]D ) +100° (c, 2.68, CHCl3); 1H
Exp er im en ta l Section
1
All melting and boiling points were uncorrected. H NMR
spectra were recorded at 200.13 MHz. The 31P NMR spectra
were measured at 81.0 and 121.49 MHz. Optical rotation
measurements were made with automatic photopolarimeter
(sensitivity ( 0.002°). TLC was done on silica gel (Merck Silica
60 F254) and column chromatography on Merck Silica gel 230-
400 mesh. Solvents and commercial reagents were distilled
and dried by conventional methods before use. All moisture
sensitive reactions were carried out in a dry argon atmosphere.
Starting methyltriphenylphosphonium iodide (1) was pre-
pared by quaternization of triphenylphosphine with methyl
iodide by standard method, and dimethyldiphenylphospho-
nium iodide was prepared according to the reported proce-
dure.23a,b Methyl p-toluenesulfinate (4a ) and (-)-(S)-menthyl
p-toluenesulfinate (4b) were prepared according to the method
described by Solladie.14 Starting methyl sulfinates 4c-h were
obtained from the corresponding sulfinyl chlorides and metha-
nol in the presence of triethylamine according to the method
described by Douglas24 and Brownbridge.25
NMR (CDCl3) δ 2.39 (s, 3H), 3.80 (s, 3H), 6.67 (d, 1H, J AB
15.5 Hz), 6.87-7.67 (m, 9H).
)
(1E ,3E )-(+)-(R )-1-(p -T o ly ls u lfin y l)-1,3-p e n t a d ie n e
(8h ): Mp 72-73 °C, [R]D ) +287.6 (c, 0.94, acetone), [R]D
)
+158.8 (c, 0.9, CHCl3).17
(+)-(R)-1-(p-Tolylsu lfin yl)eth en e (8i): Colorless oil; [R]D
) +389.7 (c, 0.76, EtOH); 1H NMR (CDCl3) δ 2.40 (s, 3H), 5.88
(d, 1H, J ) 9.5 Hz) 6.18 (d, 1H, J ) 16.5 Hz), 6.55 (dd, 1H, J
) 16.5 Hz, J ) 9.5 Hz), 7.28-7.53 (m, 4H).4a,5,8
(E)-(+)-(R)-1-(p-Tolylsu lfin yl)-1,3-bu ta d ien e (8j): Color-
less oil; [R]D ) +283.3 (c, 0.56, CHCl3); 1H NMR (CDCl3) δ 2.30
(s, 3H), 5.40 (d, 1H, J ) 10.8 Hz) 5.54 (d, 1H, J ) 17.0 Hz),
6.38 (d, 1H, J ) 15.2 Hz) 6.39 (dt, 1H, J ) 10.5 Hz, J ) 17.0
Hz), 6.99 (dd, 1H, J ) 15.2 Hz, J ) 10.3 Hz) 7.27-7.53 (m,
4H).18a
(1E,3E)-(+)-(R)-1-(p-Tolylsu lfin yl)-4-p h en yl-1,3-bu ta d i-
en e (8k ): Mp ) 102.5 °C, [R]D ) +224.9 (c, 0.55, acetone), [R]D
) +168.2 (c, 0.82, CHCl3); 1H NMR (CDCl3) δ 2.41 (s, 3H),
6.43 (d, 1H, J ) 14.7 Hz), 6.80-6.84 (m,2H), 7.14 (ddd, 1H, J
) 14.7 Hz, J ) 8.3 Hz, J ) 1.9 Hz), 7.29-7.58 (M, 9H).17,18a
Op tica lly Active (+)-(S)-(r-Su lfin ylm eth yl)tr ip h en yl-
p h osp h on iu m Iod id e (5a ). To a solution of methyltriph-
enylphosphonium iodide (2) (1.21 g, 3 mmol) in dry THF (35
mL) at -20 °C was added n-BuLi (2.1 mL of 1.55 M solution
in hexanes, 3.2 mmol). The solution was stirred at -20 °C for
a further 5 min and then for 1 h at room temperature. After
this time, the mixture was cooled to -20 °C and (-)-(S)-
menthyl p-toluenesulfinate (4b) (0.471 g, 1.6 mmol) was added.
After 10 min stirring at -20 °C and 1 h at room temperature
the mixture was quenched by the addition of 50% aqueous
solution of HI (0.25 mL, 1.5 mmol). Methyltriphenylphospho-
nium iodide (2), insoluble in THF, was filtered off, and the
THF was evaporated to give the crude product 5a . To the
product water (10 mL) was added, and the mixture was
extracted with CHCl3 (3 × 15 mL). The organic layer was
washed with a water solution of Na2S2O3 and dried over Na2-
SO4. The solvent was evaporated, and the crude product was
chromatographed on silica gel using dichloromethane-metha-
nol (2%) as the eluent. Yield: 0.57 g (70%), mp 86-88 °C,
Syn th esis of Ra cem ic a n d Op tica lly Active r,â-Un sa t-
u r a ted Su lfoxid es 8a -h . Gen er a l P r oced u r e. To a solution
of methyltriphenylphosphonium iodide (2) (0.81 g, 2 mmol) in
dry C6H6 (50 mL) at room-temperature n-BuLi (1.4 mL of 1.5
M solution in hexanes, 2.1 mmol) was added, and the mixture
was stirred for 1 h. After this time, methyl or menthyl
p-toluenesulfinate (4a ,b) (1 mmol) was added and the mixture
was stirred for 1 h. Then, freshly distilled aldehydes 7a -h
(1.5 mmol) were added and the mixture was refluxed for 10
h. After this period, the mixture was cooled to room temper-
ature and quenched by the addition of 0.2 N HCl to the pH ∼
3-4. Next, water (10 mL) was added and the layers were
separated. The water layer was extracted with CHCl3 (2 × 15
mL), and combined organic layers were dried over Na2SO4.
Then, the solvents were evaporated and the crude vinyl
1
sulfoxides were analyzed by H NMR and purified by column
chromatography on silica gel using hexane-dichloromethane
as the eluent.
Ra cem ic r,â-Un sa tu r a ted Su lfoxid es 8a -h . 1-(p-Tolyl-
1
su lfin yl)-2-p h en yleth en e (8a ): H NMR (CDCl3) δ 2.40 (s,
3H), 6.43 and 6.80 [2d, J AB ) 10.6 Hz (Z), J AB ) 15.5 Hz (E),
1H], 7.09 and 7.21-7.61 [d, J AB ) 10.6 Hz (Z) and m, 10H].5
1-(p-Tolylsu lfin yl)-2-(p-ch lor op h en yl)eth en e (8b): Mp
95-97 °C; 1H NMR (CDCl3) δ 2.40 (s, 3H), 6.79 [d, J AB ) 15.5
Hz (E), 1H], 7.22-7.64 (m, 9H).26
(23) (a) Cristau, H.-J .; Ribeill, Y.; Plenat, F.; Chicke, L. Phosphorus
Sulfur 1987, 30, 135-138. (b) Cristau, H.-J .; Ribeill, Y. Synthesis 1988,
911-912.
(24) Douglas, I. B.; Norton, R. V. J . Org. Chem. 1968, 33, 2104-
2106.
(25) Brownbridge, P.; J owett, I. C. Synthesis 1988, 252-254.
(26) Mikołajczyk, M.; Grzejszczak, S.; Midura, W. H.; Zatorski, A.;
Synthesis 1975, 278-280.

9722 J . Org. Chem., Vol. 63, No. 26, 1998
Mikołajczyk et al.
[R]D ) +127.1° (c, 1.62, CHCl3); 31P NMR (CDCl3) δP +19.8
) +144.3° (c, 2.0, CHCl3); 1H NMR (CDCl3) δ 2.40 (s, 3H), 6.43
and 6.86 [2d, J AB ) 10.6 Hz (Z), J AB ) 15.5 Hz (E), 1H], 7.09
and 7.21-7.61 [d, J AB ) 10.6 (Z) and m, 10H].5
ppm; 1H NMR (CDCl3) δ 2.38 (s, 3H), 4.44 (dd, 1H, J H-H
14.3 Hz, J P-H ) 7.8 Hz), 6.70 (dd, 1H, J H-H ) 14.3 Hz, J P-H
)
)
13.5 Hz) 7.35 (d, 2H, J H-H ) 8.2 Hz) 7.50-8.16 (m, 17H). Anal.
Calcd for C26H24PSOI; C, 57.57; H, 4.46; P, 5.71; S, 5.91.
Found: C, 57.32; H, 4.30; P, 5.67; S, 5.98.
Racemic (R-sulfinylmethyl)triphenylphosphonium iodide (5a),
mp 177-179 °C, was obtained in the same way using methyl
p-toluenesulfinate (4a ).
Syn th esis of Ra cem ic a n d Op tica lly Active r,â-Un sa t-
u r a ted Su lfoxid es via th e Wittig Rea ction u n d er Tw o-
P h a se System Ca ta lyzed by (TEBA)Br . R,â-Unsaturated
sulfoxides 8a and (+)-(R)-8i were obtained from the racemic
(()-5a and optically active (+)-(S)-5a and benzaldehyde 7a and
40% aqueous formaldehyde, respectively, according to the
procedure described by Mikołajczyk.26
Syn th esis of Ra cem ic 8l-r a n d Op tica lly Active r,â-
Un sa tu r a ted Su lfoxid es 8a ,i. Gen er a l P r oced u r e. To a
stirred solution of dimethyldiphenylphosphonium iodide (0.684
g, 2 mmol) in dry THF (30 mL) at -50 °C was added n-BuLi
(2.7 mL of 1.55 M solution in hexanes, 4.2 mmol) via a
dropping funnel. The colorless diylide solution was stirred at
-50 °C for a further 5 min and 1 h at room temperature. After
this time, the mixture was cooled to -20 °C and methyl or
menthyl sulfinate 4b-h (2 mmol) was added. The mixture was
stirred for 10 min at -20 °C and 1 h at room temperature;
then freshly distilled benzaldehyde (0.23 g, 2.2 mmol) was
added, and the mixture was refluxed with stirring for 8 h. After
this period, the mixture was cooled to room temperature and
quenched by addition of 0.4 N HCl to the pH 3-4. The solvent
was evaporated, and water (10 mL) was added. The water
solution was extracted with dichloromethane (3 × 15 mL), and
the organic layer was dried (Na2SO4) and concentrated under
reduced pressure to give the crude vinyl sulfoxide which was
analyzed by 1H NMR. The resulting products were purified
by chromatography on silica gel using hexane-dichloromethane
as the eluent.
(+)-(R)-1-(p-Tolylsu lfin yl)eth en e (8i): [R]D ) +258.8° (c,
1
2.25, EtOH); H NMR (CDCl3) δ 2.40 (s, 3H), 5.88 (d, J ) 9.5
Hz, 1H), 6.18 (d, J ) 16.5 Hz, 1H), 6.55 (dd, J ) 16.5 Hz, J )
9.5 Hz, 1H), 7.28-7.53 (m, 4H).5
((p-Tolylsu lfin yl)m eth yl)d ip h en ylp h osp h in e (14). To a
solution of methyl p-tolyl sulfoxide (0.77 g, 5 mmol) in dry Et2O
(15 mL) at -10 °C PhLi [prepared from 5.5 mmol of n-BuLi
and PhBr (0.86 g 5.5 mmol)] in hexane was added dropwise,
and the mixture was stirred at this temperature for 0.5 h.
Then, the solution was cooled to -78 °C and Ph2PCl (1.2 g,
5.5 mmol) was added. After 5 min, the mixture was warmed
to room temperature, washed with water (2 mL), and dried
over MgSO4. Ether was evaporated, and the crude product was
purified by rapid column chromatography under argon using
dry ether as the eluent. Yield: 0.89 g (53%), oil after chroma-
tography. 31P NMR: δP - 29.9 ppm (CDCl3). 1H NMR
(CDCl3): δ 2.37 (s, 3H), 3.64 (dd, 1H, J H-H ) 13.15 Hz, J P-H
) 1.58 Hz), 3.75 (dd, 1H, J H-H ) 13.15, J P-H ) 1.16 Hz), 7.17-
7.57 (m, 14H).22
((p -Tolylsu lfin yl)m et h yl)d ip h en ylp h osp h in e Su lfid e
(15). To a solution of (R-sulfinylmethyl)diphenylphosphine 14)
(0.25 g, 0.74 mmol) in dry benzene (10 mL) was added
elemental sulfur (0.04 g, 1.2 mmol), at room temperature, and
the mixture was stirred at this temperature for 2 h. After
evaporation of benzene, MeOH (5 mL) was added and the
excess of sulfur was filtered off. The crude sulfide 15 was
chromatographed (10:1 benzene-acetone): Yield 0.2 g (75%);
31P NMR (CDCl3) δP 34.0 ppm; 1H NMR (CDCl3) δ 2.34 (s, 3H),
3.76 (dd, 1H, J H-H ) 13.97 Hz, J P-H ) 10.22 Hz), 4.18 (dd,
1H, J H-H ) 13.97 Hz, J P-H ) 8.28 Hz), 7.15-8.00 (m, 14H);
MS m/e (%) 370 (43) M+; 231 (61), 185 (100). Anal. Calcd for
C
20H19PS2O: C, 64.84; H, 5.17; P, 8.36; S, 17.31. Found: C,
64.98; H, 5.00; P, 8.18; S, 17.50.
((p -Tolylsu lfin yl)m et h yl)d ip h en ylm et h ylp h osp h on -
iu m Iod id e (13a ). To a solution of (R-sulfinylmethyl)diphe-
nylphosphine 14 (0.57 g, 1.7 mmol) in dry Et2O (5 mL) was
added methyl iodide (0.5 mL) at room temperature, and the
mixture was stirred overnight. The crystalline, Et2O-insoluble,
crude product was filtered off and purified by column chro-
matography (10:1 benzene-methanol): Yield 0.45 g (55%); mp
Ra cem ic r,â-Un sa tu r a ted Su lfoxid es 8l-r . 1-(Meth yl-
su lfin yl)-2-p h en yleth en e (8l): 1H NMR (CDCl3) δ 2.70 (s,
3H) 6.45 and 6.90 [2d, 1H, J AB ) 10.6 Hz (Z), J AB ) 15.4 Hz
(E)], 7.05 and 7.22 [2d, 1H, J AB ) 10.6 Hz (Z), J AB ) 15.4 Hz
(E)], 7.37-7.52 (m, 5H).27,28
1-(Eth ylsu lfin yl)-2-p h en yleth en e (8m ): Mp 55-57 °C; 1H
NMR (CDCl3) δ 1.27 (t, 3H, J ) 7.4 Hz), 2.68-2.91 (m, 2H),
6.78 and 7.19 (2d, 2H, J AB ) 15.5 Hz), 7.29-7.44 (m, 5H); MS
m/e (%) 180 (34), 91 (100). Anal. Calcd for C10H12OS: C, 66.63;
H, 6.71; S, 17.79. Found: C, 66.60; H, 6.75; S, 17.83.
1-(n -P r op ylsu lfin yl)-2-p h en yleth en e (8n ): Mp 56-58 °C;
1H NMR (CDCl3) δ 1.06 (t, 3H, J ) 7.4 Hz), 1.69-1.96 (m,
2H), 2.76 (t, 2H, J ) 7.5 Hz), 6.81 (d, 1H, J AB ) 15.5 Hz), 7.17-
7.67 (m, 6H); MS m/e (%) 194 (17), 135 (100). Anal. Calcd for
1
104-106 °C; 31P NMR (CDCl3) δ 20.2 ppm; H NMR (CDCl3)
δ 2.33 (s, 3H), 2.97 (d, 3H, J P-H ) 13.92 Hz), 4.47 (dd, 1H,
J H-H ) 14.43 Hz, J P-H ) 8.40 Hz), 5.84 (dd, 1H, J H-H ) 14.4
Hz, J P-H ) 12.76 Hz), 7.29-8.20 (m, 14H); MS m/e (%) 215
(11), 200 (100), 185 (50). Anal. Calcd for C21H22PSOI: C, 52.51;
H, 4.62; P, 6.45; S, 6.68. Found: C, 52.34; H, 4.55; P, 6.48; S,
6.47.
1-(p-Tolylsu lfin yl)-2-p h en yleth en e (8a ). To a stirred
solution of ((p-tolylsulfinyl)methyl)diphenylmethylphosphonium
iodide (13a ) (0.96 g, 2 mmol) in dry THF (25 mL) at - 50 °C
was added n-BuLi (1.35 mL of a 1.55 M solution in hexanes,
2.1 mmol) via dropping funnel. The colorless solution was
stirred for 1 h. Then, benzaldehyde (0.23 g, 2.2 mmol) was
added and the mixture was refluxed for 10 h and worked up
as described above. The ratio E/Z of was determined by 1H
NMR spectroscopy (see Scheme 7).
C
11H14OS: C, 68.00; H, 7.26; S, 16.50. Found: C, 67.99; H,
7.19; S, 16.56.
1-(Isop r op ylsu lfin yl)-2-p h en yleth en e (8o): Mp 49-51
°C; 1H NMR (CDCl3) δ 1.21 (d, 3H, J ) 7.0 Hz), 1.25 (d, 3H, J
) 7.0 Hz), 2.73-2.98 (m, 1H), 6.73 (d, 1H, J AB ) 15.5 Hz) 7.11-
7.43 (m, 6H); MS m/e (%) 194 (2), 152 (100). Anal. Calcd for
C
11H14OS: C, 68.00; H, 7.26; S, 16.50. Found: C, 67.98; H,
7.20; S, 16.52.
1-(ter t-Bu tylsu lfin yl)-2-p h en yleth en e (8p ): Mp 69-71
1
°C; H NMR (CDCl3) δ 1.29 (s, 9H), 6.79 (d, 1H, J AB ) 15.5
Ack n ow led gm en t. One of us (M.M.) gratefully
acknowledges an award from the Alexander von Hum-
boldt Foundation that facilitated the preparation of the
final form of this paper.
Hz) 7.20-7.49 (m, 6H); MS m/e (%) 152 (100). Anal. Calcd for
C
12H16OS: C, 69.19; H, 7.74; S, 15.39. Found: C, 69.25; H,
7.70; S, 15.45.
1-(P h en ylsu lfin yl)-2-ph en yleth en e (8r ): 1H NMR (CDCl3)
δ 6.48 and 6.83 [2d, 1H, J AB ) 10.5 Hz (Z), J AB ) 15.6 Hz (E)],
7.29-7.72 (m, 11H).26
Su p p or tin g In for m a tion Ava ila ble: 1H NMR spectra for
compounds 8c-f,m -p , 5a , 13a , and 15 (12 pages). This
material is contained in libraries on microfiche, immediately
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.
Op tica lly Active r,â-Un sa tu r a ted Su lfoxid es 8a ,i. (+)-
(R)-1-(p-Tolylsu lfin yl)-2-p h en yleth en e (8a ) (E:Z/97:3): [R]D
(27) Mikołajczyk, M.; Grzejszczak, S.; Zatorski, A. J . Org. Chem.
1975, 40, 1979-1984.
(28) Mikołajczyk, M.; Grzejszczak, S.; Midura, W. H.; Zatorski, A.
Synthesis 1976, 396-398.
J O981100E