Highly stereoselective synthesis of trisubstituted α/β-unsaturated sulfoxides by heck reaction

Full text of DOI:10.1021/jo010255a

J . Org. Chem. 2001, 66, 4453-4456
4453
1-p-tolylsulfinyl-1-heptene (E)-17 was treated with iodo-
benzene or p-methoxyphenyl diazonium tetrafluoroborate
under the optimal conditions previously found in the
Heck arylation of â-sulfinyldihydrofurans and cyclo-
pentenes:5 Pd(OAc)2 as catalyst, Ag2CO3 as base, a bi-
dentate ligand (dppp or dppf), and a polar solvent
(CH3CN or DMF). However, either a sluggish transfor-
mation or no reaction at all was observed in all cases.
As the best result a 40% conversion was detected after
treating (E)-1 with excess of iodobenzene (3 equiv) in the
presence of Pd(OAc)2 (10 mol %), Ag2CO3 (200 mol %),
dppf (10 mol %) in DMF at 100 °C for 29 h8 (Scheme 1).
To overcome the poor reactivity of disubstituted R,â-
unsaturated p-tolyl sulfoxides in Heck reactions, we
reasoned that the introduction of a palladium coordinat-
ing group, such as a Me2N moiety, in the ortho position
of the arylsulfinyl moiety (substrates 2) could enhance
the rate of the process due to the possible coordination
of the arylpalladium intermediate species with the
nitrogen atom of the Me2N group. This previous coordi-
nation would presumably facilitate the further olefin
coordination/insertion steps9 (Scheme 2).
To test this idea, R,â-unsaturated 2-(N,N-dimethylami-
no)phenyl sulfoxides 2 were readily prepared by depro-
tonation of 2-(N,N-dimethylamino)phenyl methyl sulfox-
ide10 (LDA, THF, -78 °C), addition of the corresponding
aldehyde, and subsequent mesylation (MsCl, Et3N,
CH2Cl2) and basic elimination (DBU). The vinyl sulfox-
ides 2 were obtained in good yields (53-72%) as E/ Z
mixtures, in which the E isomer clearly predominated
(Table 1). Both stereoisomers were readily separated by
simple flash chromatography.
Gratifyingly, a fast and clean evolution was observed
in the palladium-catalyzed reactions of the â-alkyl-
substituted vinyl sulfoxides (E)-2a ,b with different io-
doarenes under the same experimental conditions pre-
viously used with sulfoxide (E)-1 [Pd(OAc)2, Ag2CO3, dppf,
DMF, 100 °C]. In most cases a complete evolution was
observed in 2-4 h, affording the trisubstituted vinyl
sulfoxides 3-5 in good yields (66-75%) and as single
stereoisomers (Table 2). However, unlike the reaction of
2a with iodobenzene and p-iodoanisole, its reaction with
p-nitroiodobenzene was much slower, being observed a
67% conversion yield after 91 h. The trisubstituted olefin
(E)-5a was isolated in 58% yield (87% in converted yield).
The E stereochemistry of alkenes 3-5 was the expected
according to the mechanism of the Heck reaction (ste-
High ly Ster eoselective Syn th esis of
Tr isu bstitu ted r,â-Un sa tu r a ted Su lfoxid es
by Heck Rea ction
Ine´s Alonso and J uan C. Carretero*
Departamento de Quı´mica Orga´nica, Facultad de Ciencias,
Universidad Auto´noma de Madrid, 28049 Madrid, Spain
juancarlos.carretero@uam.es
Received March 8, 2001
During the last two decades R,â-unsaturated sulfoxides
have been widely used in a variety of highly diastereo-
selective processes, such as Michael additions or Diels-
Alder cycloadditions, because of the high stereochemical
control usually exerted by the sulfinyl group.1 Although
simple R,â-unsaturated sulfoxides are easily prepared by
different methods2 (especially by Wadsworth-Emmons
olefination and condensation of R-sulfinyl carbanions
with carbonyl compounds and further dehydration), often
E/ Z mixtures of stereoisomers are obtained.1,2 From a
synthetic point of view, this problem is particularly
important in the case of the stereoselective synthesis of
acyclic trisubstituted R,â-unsaturated sulfoxides.
The palladium-catalyzed reaction of organic halides
with alkenes (the Heck reaction3) is nowadays a powerful
method for the stereoselective synthesis of trans disub-
stituted alkenes from terminal olefins. However, this
reaction has been much less applied to the stereoselective
synthesis of trisubstituted alkenes from disubstituted
ones. In particular, several examples of synthesis of
trisubstituted R,â-unsaturated esters, nitriles, aldehydes,
and ketones by Heck arylation of the corresponding
disubstituted conjugated olefins have been reported in
recent years.4 In connection with our previous work on
the application of sulfoxides as chiral auxiliaries in
asymmetric Heck reactions,5 we describe here the first
examples of synthesis of trisubstituted R,â-unsaturated
sulfoxides by highly stereoselective Heck arylation of
appropriately substituted vinyl sulfoxides.6
Resu lts a n d Discu ssion
First, to check the reactivity of acyclic 1,2-disubstituted
R,â-unsaturated sulfoxides in Heck reactions, the known
(1) Recent reviews: (a) Mikolajczk, M.; Drabowicz, J .; Kielbasinski,
P. In Chiral Sulfur Reagents. Applications in Asymmetric and Stereo-
selective Synthesis; CRC Press: Boca Raton, 1997. (b) Garc´ıa Ruano,
J . L.; Cid de la Plata, B Top. Curr. Chem. 1999, 204, 1. (c) Carren˜o,
M. C. Chem. Rev. 1995, 95, 1710.
(2) The Chemistry of Sulfones and Sulfoxides; Patai, S.; Rappoport,
Z.; Stirling, C. Eds.; J . Wiley & Sons: Chichester, 1988.
(5) (a) Priego, J .; Carretero, J . C. Synlett 1999, 1603. (b) D´ıaz Buezo,
N.; Alonso, I.; Carretero, J . C. J . Am. Chem. Soc. 1998, 120, 7129.
(6) For the synthesis of a disubstituted R,â-unsaturated sulfoxide
by a Heck reaction on p-tolyl vinyl sulfoxide, see: Somei, M.; Yamada,
F.; Ohnishi, H.; Makita, Y.; Kuriki, M. Heterocycles 1987, 26, 2823.
(7) Kosugi, H.; Kitaoka, M.; Tagami, K.; Takahashi, A.; Uda, H. J .
Org. Chem. 1987, 52, 1078. (E)-1 was prepared from methyl p-tolyl
sulfoxide following the same experimental procedure used for the
synthesis of sulfoxides 2.
(8) A very low reactivity was observed in the reaction of (E)-1 with
diazonium salts. On the other hand, the stereoisomer (Z)-1 was even
less reactive giving rise the corresponding Heck product in 5% yield
after 29 h at 100 °C.
(9) For the participation of Pd-N coordinated complexes in the Heck
reaction of amino olefins, see: Larhed, M, Andersson, C.; Hallberg, A.
Tetrahedron 1994, 50, 285 (and references therein).
(10) 2-(N,N-Dimethylamino)phenyl methyl sulfoxide was readily
prepared by methylation of o-aminothiophenol (NaH, MeI, DMF, 0 °C
to room temperature) and oxidation (MCPBA, CH2Cl2, -78 °C).
(3) For some recent reviews on the Heck reaction, see: (a) Be-
letskaya, I. P.; Cheprakov, A. V. Chem. Rev. 2000, 100, 3009. (b) Bra¨se,
S.; de Meijere, A. In Metal-catalyzed Cross-coupling Reactions; Dieder-
ich, F.; Stang, P. J ., Eds.; Wiley-VCH: Weinheim, 1998; chapter 3. (c)
Crisp, G. T. Chem. Soc. Rev. 1998, 27, 427. (d) Shibasaki, M.; Boden,
C. D. J .; Kojima, A. Tetrahedron 1997, 53, 7371. (e) Gibson, S. E.;
Middleton, R. J . Contemp. Org. Synth. 1996, 3, 447. (f) Cabri, W.;
Candiani, I. Acc. Chem. Res. 1995, 28, 2. (g) de Meijere, A.; Meyer, F.
E. Angew. Chem., Int. Ed. Engl. 1994, 36, 2379.
(4) (a) Gu¨rtler, C.; Buchwald, S. L. Chem. Eur. J . 1999, 5, 3107. (b)
Ko¨nig, W. A.; Stenzel, W.; Schotten, T. Tetrahedron Lett. 1999, 40,
2101. (c) Beller, M.; Riermeier, T. H.; Eur. J . Inorg. Chem. 1998, 29.
(d) Moreno-Man˜as, M.; Pleixats, R.; Roglans, A. Synlett 1997, 1157.
(e) Arcadi, A.; Cacchi, S.; Fabrizi, G.; Marinelli, F.; Pace, P. Tetrahedron
1996, 52, 6983. (f) Cacchi, S.; Ciattini, P. G.; Morena, E.; Pace, P.
Synlett 1996, 545. (g) Arcadi, A.; Cacchi, S.; Fabrizi, G.; Marinelli, F.;
Pace, P. Synlett 1996, 568.
10.1021/jo010255a CCC: $20.00 © 2001 American Chemical Society
Published on Web 05/22/2001

4454 J . Org. Chem., Vol. 66, No. 12, 2001
Notes
Sch em e 1
Sch em e 3
Sch em e 2
Ta ble 1. Syn th esis of r,â-Un sa tu r a ted
o-(N,N-Dim eth yla m in o)p h en ylsu lfoxid es
R
product
E/Za
yieldb (%) [E (%)]c
the â-aryl-substituted vinyl sulfoxides (E)-2c with p-
iodoanisole afforded (E)-6 with almost complete stereo-
selectivity (E/ Z ) 97/3, 51%12 yield), while the reaction
of (E)-2d with iodobenzene gave the corresponding ste-
reoisomer (Z)-6 (Z/ E ) 94/6, 63% yield). Interestingly,
in agreement with the usual stereospecificity of the
Heck reaction, the corresponding stereoisomers (Z)-2c
and (Z)-2d reacted under the same palladium-catalyzed
conditions with p-iodoanisole and iodobenzene, respec-
tively, to provide also with very high stereoselectivity
(Z)-6 and (E)-6, respectively13 (68% and 74% yields)
(Scheme 3).
nC5H11
2a
2b
2c
2d
85/15
95/5
76/24
77/23
72 (57)
56 (53)
53 (40)
65 (48)
iPr
Ph
p-MeO(C6H4)
Determined by 1H NMR on the crude mixtures. Overall
yields from the starting methyl sulfoxide after flash chromatog-
raphy. c In brackets overall yield in pure E isomer.
a
b
Ta ble 2. Heck Ar yla tion of r,â-Un sa tu r a ted
o-(N,N-Dim eth yla m in o)p h en yl Su lfoxid es (E)-2a ,b
In summary, â,â′-disubstituted R,â-unsaturated sul-
foxides can be prepared in a highly stereoselective
manner by Heck arylation of the readily available (E) and
(Z) â-substituted R,â-unsaturated sulfoxides. This pro-
cedure relies on the use of 2-(N,N-dimethylamino)phenyl
sulfoxides, in which the Me2N group would facilitate the
Heck reaction likely due to its capability of acting as
ligand in the palladium-catalyzed pathway.
2
R
Ar
product
E/Za
yieldb (%)
2a
2a
2a
2b
2b
nC5H11 Ph
nC5H11 p-MeO(C6H4)
nC5H11 p-NO2(C6H4)
iPr
iPr
3a
4a
5a
3b
4b
>98/<2
98/2
95/5
>98/<2
>98/<2
75
70
58 (87)c
75
Ph
(11) The NOESY spectrum of (E)-3a shows a strong cross-peak
between the olefinic proton and the ortho hydrogens of the phenyl
group. Similarly, in the case of 4a the same strong NOE effect was
present in (E)-4a but absent in (Z)-4a .
(12) In this case the regioisomer 1-[2-(N,N-dimethylamino)phenyl-
sulfinyl]-1-(4-methoxyphenyl)-2-phenylethene was isolated as a minor
compound (14% yield).
(13) The stereochemical assignment of isomers 6 was unambiguously
established by NOESY experiments. Thus, in a mixture Z/ E (ratio
88/12), the major product (Z)-6 showed a strong cross-peak between
the olefinic proton and those of the ortho position to the phenyl group
[this correlation is not present in (E)-6]. Similarly, a strong correlation
is observed between the olefinic proton and those of the ortho position
of the p-methoxyphenyl substituent in (E)-6, but not in (Z)-6.
p-MeO(C6H4)
66
Determined by 1H NMR on the crude mixtures. In pure
a
b
compound after flash chromatography. c Conversion yield.
reospecific syn Pd-C insertion and syn â-H elimination
steps) and was unequivocally proved by NOESY experi-
ments in 3a and 4a .11
This methodology has also been applied to the highly
stereoselective preparation of â,â′-diaryl-substituted
R,â-unsaturated sulfoxides. Thus, the Heck reactions of

Notes
J . Org. Chem., Vol. 66, No. 12, 2001 4455
(E)-1-[2-(N,N-Dim eth yla m in o)p h en ylsu lfin yl]-2-(4-m eth -
oxyp h en yl)eth en e [(E)-2d ]. 1H NMR δ: 7.80 (dd, 1H, J ) 1.3
and 7.8 Hz), 7.40-7.12 (m, 3H), 7.32 (bd, 2H, J ) 8.8 Hz), 7.20
(d, 1H, J ) 15.4 Hz), 6.90 (d, 1H, J ) 15.4 Hz), 6.81 (bd, 2H, J
) 8.8 Hz), 3.74 (s, 3H), 2.73 (s, 6H). 13C NMR δ: 160.3, 151.0,
139.0, 133.8, 131.3, 129.3, 128.8, 126.9, 124.9, 124.2, 120.2, 114.0,
55.1, 44.9.
Exp er im en ta l Section
1H NMR (300 MHz) and 13C NMR (75 MHz) spectra were
recorded in CDCl3 at room temperature. Chemical shifts (ppm)
and coupling constants (Hz) were obtained by first-order analysis
of spin patterns. Mass spectra (MS) and high-resolution mass
spectra (HRMS) were recorded by using FAB technique. Mass
data are reported in mass units (m/z), and values in brackets
show the relative intensity from the base peak (as 100%). All
reagents were obtained from commercial suppliers and were
used without further purification except for aldehydes, which
were used freshly distilled. DMF was distilled from CaH2. THF
was distilled from sodium/benzophenone. CH2Cl2 was distilled
from P2O5. All reactions involving the use of LDA and Pd(OAc)2
were carried out in flame- and oven-dried glassware under inert
argon atmosphere. Chromatography was carried out using
Merck 60 230-400 mesh silica gel.
(Z)-1-[2-(N,N-Dim eth yla m in o)p h en ylsu lfin yl]-2-(4-m eth -
1
oxyp h en yl)eth en e [(Z)-2d ]. H NMR δ: 7.92 (dd, 1H, J ) 1.7
and 7.7 Hz), 7.68 (bd, 2H, J ) 8.8 Hz), 7.41 (dt, 1H, J ) 1.7 and
7.6 Hz), 7.32 (dt, 1H, J ) 1.2 and 7.6 Hz), 7.18 (dd, 1H, J ) 1.2
and 7.8 Hz), 6.90 (bd, 2H, J ) 8.8 Hz), 6.82 (d, 1H, J ) 10.6
Hz), 6.03 (d, 1H, J ) 10.6 Hz), 3.82 (s, 3H), 2.50 (s, 6H). 13C
NMR δ: 160.3, 151.5, 140.8, 136.0, 134.3, 131.6, 131.4, 126.9,
125.7, 124.8, 121.1, 113.6, 55.2, 44.8. MS: 302 (100, M+ + 1),
284 (33.0, M+ + 1 - 18). HRMS: exact mass calcd for C17H20
NO2S (M+ + 1) 302.1215, found 302.1212.
-
Gen er a l P r oced u r e for th e P r ep a r a tion of Vin yl Su l-
foxid es 2. To a solution of o-(N,N-dimethylamino)phenyl methyl
sulfoxide (500 mg, 2.7 mmol) in THF (4 mL) was added LDA
(0.5M THF solution, 6.2 mL, 3.1 mmol, 1.1 equiv) dropwise at
-78 °C under argon atmosphere. The mixture was stirred at
-78 °C for 10 min, and the corresponding aldehyde (5.4 mmol,
2 equiv) was added. Stirring was continued for 3 h while the
mixture was warmed to room temperature. The reaction was
quenched with saturated aqueous NH4Cl, and the product was
extracted with CH2Cl2. The combined extracts were dried
(MgSO4) and evaporated. The residue was dissolved in dried
CH2Cl2 (9 mL) and stirred under argon atmosphere at 0 °C. Then
MsCl (314 µL, 4.05 mmol, 1.5 equiv) and Et3N (3.7 mL, 27 mmol,
10 equiv) were added. The mixture was stirred at room tem-
perature until the intermediate mesylate disappeared by TLC
(4-5 h). The reaction was quenched with NH4Cl, and the product
was extracted with CH2Cl2, dried (MgSO4), and evaporated. The
residue was purified by flash chromatography.
(E )-1-[2-(N ,N -Dim e t h yla m in o)p h e n ylsu lfin yl]-1-h e p -
ten e [(E)-2a ]. 1H NMR δ: 7.74 (dd, 1H, J ) 1.6 and 7.8 Hz),
7.36 (dt, 1H, J ) 1.7 and 7.7 Hz), 7.20 (dt, 1H, J ) 1.2 and 7.5
Hz), 7.11 (dd, 1H, J ) 1.2 and 7.9 Hz), 6.45 (dt, 1H, J ) 6.6 and
15.1 Hz), 6.32 (dt, 1H, J ) 1.2 and 15.1 Hz), 2.69 (s, 6H), 2.16-
2.08 (m, 2H), 1.42-1.18 (m, 6H), 0.81 (bt, 3H, J ) 6.9 Hz). 13C
NMR δ: 150.9, 139.0, 138.0, 133.1, 131.1, 124.6, 124.1, 119.9,
44.8, 31.7, 31.0, 27.8, 22.2, 13.8. MS: 266 (100, M+ + 1), 248
(34.8, M+ + 1 - 18). HRMS: exact mass calcd for C15H24NOS
(M+ + 1) 266.1579, found 266.1576.
(Z)-1-[2-(N ,N -Dim e t h yla m in o)p h e n ylsu lfin yl]-1-h e p -
ten e [(Z)-2a ]. 1H NMR δ: 7.91 (dd, 1H, J ) 1.7 and 7.7 Hz),
7.41 (dt, 1H, J ) 1.7 and 7.6 Hz), 7.29 (dt, 1H, J ) 1.2 and 7.6
Hz), 7.15 (dd, 1H, J ) 1.2 and 7.7 Hz), 6.15-6.07 (m, 1H), 5.97
(dt, 1H, J ) 1.3 and 9.4 Hz), 2.72-2.62 (m, 1H), 2.68 (s, 6H),
2.50-2.40 (m, 1H), 1.55-1.28 (m, 6H), 0.95-0.88 (m, 3H). 13C
NMR δ: 151.3, 141.1, 139.8, 136.5, 131.4, 125.1, 124.8, 120.4,
44.9, 31.5, 29.4, 28.7, 22.5, 14.0. MS: 266 (100, M+ + 1), 248
(34.2, M+ + 1 - 18). HRMS: exact mass calcd for C15H24NOS
(M+ + 1) 266.1579, found 266.1574.
(E)-1-[2-(N,N-Dim eth yla m in o)p h en ylsu lfin yl]-3-m eth yl-
1-bu ten e [(E)-2b]. 1H NMR δ: 7.74 (dd, 1H, J ) 1.6 and 7.7
Hz), 7.36 (dt, 1H, J ) 1.6 and 7.3 Hz), 7.21 (dt, 1H, J ) 1.2 and
7.7 Hz), 7.11 (dd, 1H, J ) 1.2 and 7.6 Hz), 6.43 (dd, 1H, J ) 6.5
and 15.0 Hz), 6.25 (dd, 1H, J ) 1.2 and 15.0 Hz), 2.68 (s, 6H),
2.45-2.34 (m, 1H), 0.98 (d, 6H, J ) 6.9 Hz. 13C NMR δ: 151.1,
144.6, 139.2, 131.3, 131.2, 124.9, 124.3, 120.2, 44.9, 30.8, 21.5,
21.3.
Gen er a l P r oced u r e for th e Heck Rea ction of Su lfoxid es
2: Syn th esis of Tr isu bstitu ted Su lfoxid es 3-6. A mixture
of the R,â-unsaturated sulfoxide 2 (0.4 mmol), silver carbonate
(0.8 mmol, 200 mol %), Pd(OAc)2 (0.04 mmol, 10 mol %), dppf
(0.04 mmol, 10 mol %), aryl iodide (1.2 mmol, 300 mol %), and
DMF (8 mL) was heated at 100 °C under argon atmosphere.
When the sulfoxide 2 disappeared by TLC (eluent hexanes-ethyl
acetate ) 1:1) the mixture was allowed to cool to room temper-
ature, diluted with Et2O (20 mL), filtered through Celite, washed
with water (20 mL), dried (MgSO4), and evaporated. The residue
was analyzed by 1H NMR to determine the E/Z ratio and was
purified by flash chromatography (the reaction time, the E/Z
ratio, the eluent for the silica gel chromatography, and the yield
was indicated below for each case).
(E)-1-[2-(N,N-Dim eth yla m in o)p h en ylsu lfin yl]-2-p h en yl-
1-h ep ten e [(E)-3a ]. Reaction time: 2 h. Eluent: hexanes-ethyl
1
acetate ) 5:2, yield: 75%. mp: 70-72 °C. H NMR δ: 7.93 (dd,
1H, J ) 1.7 and 7.7 Hz), 7.39 (dt, 1H, J ) 1.7 and 7.6 Hz), 7.31-
7.24 (m, 6H), 7.15 (dd, 1H, J ) 1.3 and 7.8 Hz), 6.14 (s, 1H),
3.20-3.10 (m, 1H), 2.89-2.80 (m, 1H), 2.68 (s, 6H), 1.52-1.22
(m, 6H), 0.85 (bt, 3H, J ) 7.1 Hz). 13C NMR δ: 152.1, 151.3,
140.4, 139.2, 133.6, 131.3, 128.6, 128.4, 126.5, 125.3, 124.7, 120.8,
45.0, 31.7, 31.4, 28.3, 22.3, 13.9. Anal. Calcd for C21H27NOS: C,
73.86%; H, 7.97%; N, 4.10%; S, 9.39%. Found: C, 73.81%; H,
7.60%; N, 4.31%; S, 9.39%.
(E)-1-[2-(N,N-Dim eth yla m in o)p h en ylsu lfin yl]-2-(4-m eth -
oxyp h en yl)-1-h ep t en e [(E)-4a ]. Reaction time: 3 h. E/ Z
ratio: 98/2. Eluent: hexanes-ethyl acetate ) 4:1, yield: 70%.
1H NMR δ: 7.95 (dd, 1H, J ) 1.7 and 7.7 Hz), 7.40 (dt, 1H, J )
1.8 and 7.7 Hz), 7.33-7.27 (m, 1H), 7.29 (bd, 2H, J ) 8.8 Hz),
7.17 (dd, 1H, J ) 1.3 and 7.7 Hz), 6.83 (bd, 2H, J ) 8.8 Hz),
6.13 (s, 1H), 3.77 (s, 3H), 3.18-3.08 (m, 1H), 2.90-2.80 (m, 1H),
2.68 (s, 6H), 1.53-1.25 (m, 6H), 0.88 (bt, 3H, J ) 7.1 Hz). 13C
NMR δ: 160.1, 151.7, 151.4, 140.7, 132.1, 131.3, 129.6, 127.9,
125.3, 124.8, 120.8, 113.9, 55.3, 45.1, 31.8, 31.3, 28.6, 22.5, 14.0.
Anal. Calcd for C22H29NO2S: C, 71.12%; H, 7.87%; N, 3.77%; S,
8.63%. Found: C, 70.79%; H, 7.46%; N, 3.29%; S, 8.29%.
(E)-1-[2-(N,N-Dim eth yla m in o)p h en ylsu lfin yl]-2-(4-n itr o-
p h en yl)-1-h ep ten e [(E)-5a ]. Reaction time: 91 h. Conversion
rate: 67%. E/ Z ratio: 95/5. Eluent: hexanes-ethyl acetate )
1
4:1, yield: 58%. H NMR δ: 8.18 (bd, 2H, J ) 8.9 Hz), 7.94 (dd,
1H, J ) 1.6 and 7.7 Hz), 7.49-7.43 (m, 1H), 7.48 (bd, 2H, J )
8.9 Hz), 7.35 (dt, 1H, J ) 1.3 and 7.7 Hz), 7.22 (dd, 1H, J ) 1.2
and 7.9 Hz), 6.25 (s, 1H), 3.24-3.15 (m, 1H), 2.93-2.84 (m, 1H),
2.71 (s, 6H), 1.49-1.25 (m, 6H), 0.88 (bt, 3H, J ) 7.3 Hz). 13C
NMR δ: 151.3, 149.7, 147.8, 145.8, 139.9, 136.7, 131.7, 127.6,
125.7, 124.9, 123.9, 121.0, 45.2, 31.6, 31.5, 28.2, 22.4, 13.9. MS:
387 (100, M+ + 1), 369 (30.2, M+ + 1 - 18). HRMS: exact mass
calcd for C21H27N2O3S (M+ + 1) 387.1742, found 387.1757.
(E)-1-[2-(N,N-Dim eth yla m in o)p h en ylsu lfin yl]-3-m eth yl-
2-p h en yl-1-bu ten e [(E)-3b]. Reaction time: 4 h. E/ Z ratio:
>98/<2. Eluent: hexanes-ethyl acetate ) 4:1, yield: 75%. 1H
NMR δ: 7.92 (dd, 1H, J ) 1.6 and 8.1 Hz), 7.39 (dt, 1H, J ) 1.6
and 7.7 Hz), 7.29-7.23 (m, 4H), 7.16 (dd, 1H, J ) 1.2 and 7.7
Hz), 7.13-7.07 (m, 2H), 5.88 (s, 1H), 3.84-3.75 (m, 1H), 2.74 (s,
6H), 1.22 (d, 3H, J ) 6.9 Hz), 1.14 (d, 3H, J ) 6.9 Hz). 13C NMR
δ: 158.7, 151.3, 139.8, 138.7, 134.3, 131.4, 127.9, 127.8, 127.7,
(E)-2-P h en yl-1-[2-(N,N-d im eth yla m in o)p h en ylsu lfin yl]-
1
eth en e [(E)-2c]. H NMR δ: 7.79 (dd, 1H, J ) 1.6 and 7.7 Hz),
7.38-7.33 (m, 4H), 7.29-7.18 (m, 3H), 7.24 (d, 1H, J ) 15.5 Hz),
7.12 (dd, 1H, J ) 1.1 and 7.9 Hz), 7.07 (d, 1H, J ) 15.5 Hz),
2.73 (s, 6H). 13C NMR δ: 150.9, 138.7, 134.1, 133.7, 131.9, 131.4,
129.0, 128.6, 127.3, 125.0, 124.1, 120.2, 44.9. MS: 272 (100, M+
+ 1), 254 (30.0, M+ + 1-18). HRMS: exact mass calcd for C16H18
-
NOS (M+ + 1) 272.1109, found 272.1107.
(Z)-2-P h en yl-1-[2-(N,N-d im eth yla m in o)p h en ylsu lfin yl]-
1
eth en e [(Z)-2c]. H NMR δ: 7.94 (dd, 1H, J ) 1.6 and 7.5 Hz),
7.74-7.69 (m, 1H), 7.47-7.28 (m, 6H), 7.17 (dd, 1H, J ) 1.6 and
7.5 Hz), 6.92 (d, 1H, J ) 10.2 Hz), 6.15 (d, 1H, J ) 10.2 Hz),
2.48 (s, 6H). 13C NMR δ: 151.5, 140.4, 136.6, 136.4, 134.3, 131.5,
129.7, 129.0, 128.2, 125.5, 124.8, 121.0, 44.7.
125.0, 124.9, 120.3, 45.1, 31.6, 21.9, 21.3. MS: 314 (100, M+
+
-
1), 296 (14.7, M+ + 1 - 18). HRMS: exact mass calcd for C19H24
NOS (M+ + 1) 314.1579, found 314.1587.

4456 J . Org. Chem., Vol. 66, No. 12, 2001
Notes
(E)-1-[2-(N,N-Dim eth yla m in o)p h en ylsu lfin yl]-2-(4-m eth -
oxyp h en yl)-3-m eth yl-1-bu ten e [(E)-4b]. Reaction time: 4 h.
E/ Z ratio: >98/<2. Eluent: hexanes-ethyl acetate ) 4:1,
(Z)-1-[2-(N,N-Dim eth yla m in o)p h en ylsu lfin yl]-2-(4-m eth -
oxyp h en yl)-2-p h en yleth en e [(Z)-6]. From (Z)-2c: reaction
time: 3.5 h, conversion rate: 100%. Z/ E ratio: 94/6, yield: 68%.
From (E)-2d : reaction time: 24 h, conversion rate: 95%. Z/ E
ratio: 97/3, yield: 63%. Eluent: hexanes-ethyl acetate ) 4:1.
1H NMR δ: 8.00 (bd, 1H, J ) 7.7 Hz), 7.46 (bd, 2H, J ) 8.5 Hz),
7.45-7.40 (m, 1H), 7.32-7.20 (m, 6H), 7.13 (bd, 1H, J ) 7.3 Hz),
6.97 (bd, 2H, J ) 8.5 Hz), 6.45 (s, 1H), 3.87 (s, 3H), 2.56 (s, 6H).
13C NMR δ: 160.1, 151.9, 151.2, 140.3, 139.8, 132.7, 131.7, 131.4,
129.8, 129.2, 128.5, 128.3, 124.9, 124.4, 120.0, 113.4, 55.3, 44.6.
MS: 378 (100, M+ + 1), 360 (29.4, M+ + 1 - 18). HRMS: exact
mass calcd for C23H24NO2S (M+ + 1) 378.1528, found 378.1518.
1
yield: 66%. H NMR δ: 7.93 (dd, 1H, J ) 1.6 and 7.7 Hz), 7.40
(dt, 1H, J ) 1.6 and 7.7 Hz), 7.27 (dt, 1H, J ) 1.2 and 7.7 Hz),
7.16 (dd, 1H, J ) 1.2 and 8.1 Hz), 7.07 (bd, 2H, J ) 8.9 Hz),
6.79 (bd, 2H, J ) 8.9 Hz), 5.87 (s, 1H), 3.83-3.74 (m, 1H), 3.76
(s, 3H), 2.73 (s, 6H), 1.24 (d, 3H, J ) 6.9 Hz), 1.16 (d, 3H, J )
6.9 Hz). 13C NMR δ: 159.1, 158.3, 151.2, 139.8, 133.8, 131.3,
131.0, 129.0, 124.9, 124.7, 120.2, 113.1, 55.1, 45.0, 31.6, 21.9,
21.3. MS: 344 (100, M+ + 1), 326 (33.2, M+ + 1 - 18). HRMS:
exact mass calcd for C20H26NO2S (M+ + 1) 344.1684, found
344.1681.
(E)-1-[2-(N,N-Dim eth yla m in o)p h en ylsu lfin yl]-2-(4-m eth -
oxyp h en yl)-2-p h en ylet h en e [(E)-6]. From (E)-2c: reaction
time: 24 h, conversion rate: 85%. E/ Z ratio: 97/3, yield: 51%.
From (Z)-2d : reaction time: 3.5 h, conversion rate: 100%. E/ Z
ratio: 93/7, yield: 74%. Eluent: hexanes-ethyl acetate ) 4:1.
1H NMR δ: 7.99 (dd, 1H, J ) 1.6 and 7.7 Hz), 7.51-7.38 (m,
6H), 7.27 (dt, 1H, J ) 1.2 and 7.7 Hz), 7.14 (bd, 2H, J ) 8.9 Hz),
7.10 (dd, 1H, J ) 1.2 and 8.1 Hz), 6.78 (bd, 2H, J ) 8.9 Hz),
6.46 (s, 1H), 3.76 (s, 3H), 2.50 (s, 6H). 13C NMR δ: 160.6, 151.6,
151.2, 139.8, 137.5, 132.0, 131.5, 131.4, 130.2, 129.7, 128.7, 127.9,
124.8, 124.3, 119.8, 113.7, 55.2, 44.5. MS: 378 (100, M+ + 1),
Ack n ow led gm en t. We are grateful to the Ministe-
rio de Educacio´n y Cultura (project PB96-0021) and
Ministerio de Ciencia y Tecnolog´ıa (project BQU2000-
0226) for financial support.
Su p p or tin g In for m a tion Ava ila ble: 13C NMR spectra of
all new compounds and NOESY spectra of (E)-6 and (Z)-6. This
material is available free of charge via the Internet at
http://pubs.acs.org.
360 (27.5, M+ + 1 - 18). HRMS: exact mass calcd for C23H24
NO2S (M+ + 1) 378.1528, found 378.1538.
-
J O010255A