Reactions of p-toluenesulfenyl chloride with enol acetates. The synthetic potential of the resulting adducts

Article abstract of DOI:10.1007/s11172-005-0314-4

Reactions of vinyl and propen-2-yl acetates with p-toluenesulfenyl chloride afforded the corresponding α-chloro-β-(p-tolyl)thioalkyl acetates in nearly quantitative yields.These adducts reacted with some C-nucleophiles in the presence of Lewis acids to gi

Full text of DOI:10.1007/s11172-005-0314-4

Russian Chemical Bulletin, International Edition, Vol. 54, No. 3, pp. 743—747, March, 2005
743
Reactions of pꢀtoluenesulfenyl chloride with enol acetates.
The synthetic potential of the resulting adducts
ꢀ
W. A. Smit, E. A. Yagodkin, and G. V. Zatonsky
N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences,
47 Leninsky prosp., 119991 Moscow, Russian Federation.
Fax: +7 (095) 135 5328. Eꢀmail: smt@ioc.ac.ru
Reactions of vinyl and propenꢀ2ꢀyl acetates with pꢀtoluenesulfenyl chloride afforded the
corresponding αꢀchloroꢀβꢀ(pꢀtolyl)thioalkyl acetates in nearly quantitative yields. These adꢀ
ducts reacted with some Cꢀnucleophiles in the presence of Lewis acids to give the correspondꢀ
ing alkylation products.
Key words: enol acetates, arenesulfenyl chlorides, electrophilic addition, Cꢀnucleophiles,
βꢀarylthioalkylation.
Electrophilic addition of arenesulfenyl halides to a
carbon—carbon multiple bond belongs to the wellꢀstudꢀ
ied reactions of alkenes of various types.1 As a rule, this
reaction occurs under mild conditions, giving rise to aryl
βꢀhaloalkyl sulfides in nearly quantitative yields. Apart
from being suitable for functionalization of a double
bond, this reaction is preparatively valuable because the
resulting adducts can also be used as electrophilic reꢀ
agents, which react in the presence of Lewis acids with
a broad range of Cꢀnucleophiles (NuC) of the πꢀdonor
type to form a new carbon—carbon bond.2 Presumꢀ
ably, this reaction proceeds through the formation of a
cationoid intermediate of the episulfonium ion (ESI) type
(Scheme 1).
formations leading to polyfunctional derivatives, as has
been shown by us earlier.2,3
To extend the area of synthetic application of these
transformations, it was expedient to study the possible use
of acetoxy alkenes (R = OAc) as the starting unsaturated
substrates. The literature data on reactions of arenesulfenyl
halides with such alkenes are virtually lacking. Indeed,
the reaction of benzenesulfenyl chloride with vinyl acꢀ
etate was mentioned in only one study:4 its rate constant
was reported to be two to three orders of magnitude lower
than the rate constants for common alkenes. However, no
properties of the adduct obtained were reported, except
for its 1H NMR spectrum.
Vinyl ethers are known5 to virtually instantaneously
react with ArSCl even at –70 °C. We found that vinyl
acetate 1 does not react with pꢀTolSCl under these condiꢀ
tions (the characteristic color of sulfenyl halide persisted
for 2 h). However, the roomꢀtemperature reaction was
completed over 5 min. The resulting adduct 2 was isolated
in 95% yield (Scheme 2). Its structure was established
from analytical and spectroscopic data. Interestingly, adꢀ
duct 2 is hydrolytically stable and withstands column chroꢀ
matography on silica gel, while analogous products obꢀ
Scheme 1
Scheme 2
i. Lewis acid.
R = Alk, Ar, OAlk; X = O, CH2; M = Si, Sn; R´ = Alk
This type of a transformation has been studied in most
detail for adducts obtained from alkoxyalkenes (R = OAlk)
since, in particular, the resulting coupling products are
promising for sequential intraꢀ and intermolecular transꢀ
i. ArSCl; ii. H2O for R = Me.
R = H (1, 2), Me (3, 4), Ar = pꢀTol.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 730—734, March, 2005.
1066ꢀ5285/05/5403ꢀ0743 © 2005 Springer Science+Business Media, Inc.

744
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 3, March, 2005
Smit et al.
tained from vinyl ethers usually cannot be isolated in
the individual state.5 As expected, the reaction of propenꢀ
2ꢀyl acetate 3 with pꢀTolSCl occurs sufficiently easily
even at –30 °C. However, on attempted isolation and
purification, the corresponding adduct 4 readily hydroꢀ
lyzed to give (pꢀtolylthio)acetone (5) in 95% yield. The
phenolate) (MABR)—TMSOTf are known6 to be espeꢀ
cially strong Lewis acids. Use of these systems in the
reaction of compound 2 with acetal 6 increased the yield
of product 7 to 50—60%.
However, in these cases as well, the reaction occurred
only at room temperature, which reduces its overall effiꢀ
ciency and the possibility of its application to less reactive
NuC. A more successful alternative procedure involves
silver salts as specific Lewis acids which irreversibly bind
the leaving chloride anion. When adduct 2 was treated
with silver triflate in CH2Cl2, a precipitate formed even at
–15 °C. The direct reaction product could be expected to
be a cationoid acetoxyꢀESI intermediate (Scheme 4).
However, the latter seems to be kinetically unstable, beꢀ
cause subsequent treatment of the reaction mixture with
nucleophiles (MeOH or NuC) gave no expected "quenchꢀ
ing" products from the suggested intermediate; instead,
βꢀarylthio acylal 8 was isolated as the major product inꢀ
stead. We did not investigate the reaction mechanism
involved; most likely, this product is formed in the reacꢀ
tion of the generated intermediate with the starting subꢀ
strate 2 (Scheme 4).
The reaction of adduct 2 with AgOTf was found to be
synthetically useful in the presence of such Cꢀnucleoꢀ
philes as ketene silyl acetals (6 or 9), enol silyl ethers
(e.g., 10), or allylstannanes (11 or 12). These nucleoꢀ
philes trap the in situ generated cationoid to give the
corresponding alkylation products 7 and 13—16 in good
or satisfactory yields (Scheme 5). The preparation of adꢀ
duct 7 in acetonitrile and nitromethane demonstrated that
these solvents are also suitable for this reaction.
1
in situ obtained product 4 was characterized by H NMR
data; the absence of signals of impurities in its specꢀ
trum allowed subsequent use of this adduct without puriꢀ
fication.
As already noted, βꢀarylthioꢀαꢀchloroalkyl ethers (obꢀ
tained from arenesulfenyl chlorides and alkoxyalkenes)
form reactive cationoid ESI intermediates in the presence
of Lewis acids even at –70 °C (see Scheme 1); these ions
alkylate various Cꢀnucleophiles (NuC).2,3 As expected,
because of the deactivating effect of the acetoxy substituꢀ
ent, βꢀarylthioꢀαꢀchloroalkyl acetates 2 and 4 proved to
be substantially less reactive in analogous transformations.
For instance, adduct 2 remained intact on treatment with
such Lewis acids as TiCl4, TMSOTf, and LiClO4/MeNO2
in CH2Cl2 over the temperature range from –70 to 0 °C
(TLC data). In an attempt to use adduct 2 for the in situ
generation of a cationoid intermediate under the action
of TiCl4 at room temperature in the presence of such a
reactive Cꢀnucleophile as dimethylketene methyl triꢀ
methylsilyl acetal 6, no formation of the expected alkylaꢀ
tion product 7 was observed (see below); after several
hours, complete resinification of the reaction mixture ocꢀ
curred. Encouraging results were obtained with the use of
stronger Alꢀcontaining Lewis acids. Indeed, the reaction
with Et2AlCl or EtAlCl2 afforded adduct 7, though in low
yield (5—10%). The mixed systems Et2AlCl—TMSOTf
or methylaluminum bis(4ꢀbromoꢀ2,6ꢀdiꢀtertꢀbutylꢀ
The presence of an additional methyl group in adduct
4 substantially alters its properties compared to product 2.
Our attempts to carry out the reaction of adduct 4 with
acetal 6 in the presence of such Lewis acids as TMSOTf,
TiCl4, Et2AlCl, and LiClO4/MeNO2 in the temperature
range from –78 to 20 °C failed: in all cases, the major
product was (pꢀtolylthio)acetone 5 isolated by convenꢀ
tional workꢀup of the reaction mixture (ether—aqueous
NaHCO3). Since compound 4 is easily hydrolyzed in
aqueous media to compound 5 (see above), these results
allowed, by themselves, no conclusions to be drawn eiꢀ
ther about the assumed generation of a cationoid interꢀ
mediate from compound 4 or about its reactivity. For this
reason, we studied the reaction of compound 4 with
Scheme 3
1
TMSOTf (1 : 1 ratio) in CD2Cl2 by H NMR spectroꢀ
scopy. It was found that the spectrum of adduct 4 at
–70 °C remains unchanged for 1 h. However, signals for
ketone 5 appeared at –30 °C (15 min, 4 : 5 = 8 : 1) and
became dominant at higher temperatures (0 °C, 15 min,
4 : 5 = 1 : 2; 10 °C, 5 min, 4 : 5 = 20 : 1). Simultaneously,
TMSCl and AcOTf accumulated in the reaction mixture
(signals at δ 0.4 and 2.6, respectively). Hence, the chloꢀ
ride anion and the acetyl cation are eliminated concertꢀ
edly under these conditions (Scheme 6).
Ar = pꢀTol
Reagents and conditions: Lewis acid, 20 °C, CH2Cl2.
Lewis acid
Et2AlCl
EtAlCl2
Et2AlCl—TMSOTf
MABR—TMSOTf
Yield (%)
10
5
50
60

Reactions of ArSCH2CH(R)ClOAc with Cꢀnucleophiles Russ.Chem.Bull., Int.Ed., Vol. 54, No. 3, March, 2005
745
Scheme 4
Ar = pꢀTol
Scheme 5
Scheme 6
Ar = pꢀTol
ence of TMSOTf at –40 °C gave a mixture of allylation
products 17a—c in 70% total yield. However, compound
4 did not react with dimethylketene trimethylsilyl acetal 6
under the same conditions; ketone 5 was isolated as the
only product. In contrast, the reaction of compound 4
with methallylstannane 12 as NuC in the presence of
AgOTf at 0 °C smoothly gave product 18 in good yield.
A comparison of the results obtained with the known
data on the properties of ArSCl—alkene adducts2,7 sugꢀ
gests that the presence of an acetoxy substituent in adꢀ
ducts of the type 2 and 4 substantially reduces their abiliꢀ
ties to generate cationoid intermediates under the action
of Lewis acids. Moreover, it is incorrect to regard these
intermediates in Lewis acid—catalyzed reactions of adꢀ
ducts 2 and 4 with Cꢀnucleophiles as kinetically stable
species, as was the case in previous examples (see above).
Apparently, the transformations of adducts 2 and 4 into
alkylation products of the aforementioned type (see
Schemes 5, 7) would be more correctly described in terms
of the SN2 mechanism. Note that according to the literaꢀ
ture data,8 nucleophilic substitution reactions in the seꢀ
ries of related compounds such as αꢀchloroalkyl acetates
It also follows from the results obtained that a search
for the possibility of using the adduct 4—Lewis acid sysꢀ
tem as an electrophile in reactions with NuC is stringently
limited: the reaction temperature should be as low as
possible and silylꢀcontaining NuC cannot be used (in reꢀ
actions with the latter, TMSOTf is regenerated). Indeed,
the reaction of adduct 4 with allylstannane 11 in the presꢀ

746
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 3, March, 2005
Smit et al.
Scheme 7
Ar = pꢀTol
96%) as a slightly colored oil, Rf 0.4 (hexane—ethyl acetate,
5 : 1). Elemental analysis data were irreproducible because of
the instability of the adduct. Its purity was confirmed by the data
from the 1H NMR spectrum which was free from signals of
impurities. 1H NMR, δ: 7.35, 7.15 (both d, 4 H each, Ar); 4.00,
3.40 (both d, AB system, 2 H, CH2, JAB = 14 Hz); 2.25 (s, 3 H,
Me—Ar); 1.95 (s, 3 H, MeCOO); 1.75 (s, 3 H, Me).
can follow both the SN1 and SN2 mechanisms depending
on the nature of substrates and reagents.8
Thus, easily accessible adducts from acetoxy alkenes
and arenesulfenyl chlorides can be used as electrophilic
reagents for the formation of a new carbon—carbon bond.
This makes it promising to further develop both preparaꢀ
tive conditions for these reactions and the synthetic poꢀ
tential of the resulting polyfunctional adducts.
1ꢀ(4ꢀTolylthio)propanꢀ2ꢀone (5). When chromatographed on
silica gel, adduct 4 obtained from acetate 3 as described above
completely converted into ketone 5. The yield of propanone 5 as
a colorless oil from acetate 3 (100 mg) was 170 mg (95%), Rf 0.4
Experimental
1
(hexane—ethyl acetate, 5 : 1). H NMR, δ: 7.35, 7.15 (dd, 4 H,
Ar); 3.60 (s, 2 H, CH2); 2.30 (s, 3 H, Me—Ar); 2.25 (s,
All experiments were carried out in an atmosphere of dry
argon in solvents dried according to standard procedures. TLC
analysis was performed on Merck chromatographic plates (SiO2,
220—440 mesh, ASTM). 1H and 13C NMR spectra were reꢀ
corded in CDCl3 on a Bruker WMꢀ250 instrument. Commercial
EtAlCl2, Et2AlCl, AlMe3, AgOTf, TMSOTf (Aldrich), allyl(triꢀ
nꢀbutyl)stannane (Lancaster Co.), 4ꢀbromoꢀ2,6ꢀdiꢀtertꢀbutylꢀ
phenol, vinyl acetate, and propenꢀ2ꢀyl acetate (Acros Co.) were
used. Triꢀnꢀbutyl(methallyl)stannane was prepared as described
earlier.9 Siloxyalkenes employed as Cꢀnucleophiles were preꢀ
pared according to a known procedure.10 pꢀToluenesulfenyl chloꢀ
ride was synthesized by the reaction of 4ꢀmethylbenzenethiol
with sulfuryl chloride.11
1ꢀChloroꢀ2ꢀ(4ꢀtolylthio)ethyl acetate (2). pꢀToluenesulfenyl
chloride (135 mg, 0.84 mmol) was added at 20 °C to a solution
of vinyl acetate (1) (73 mg, 0.84 mmol) in CH2Cl2 (5 mL).
Stirring for 5 min resulted in complete decoloration of the soluꢀ
tion. The solvent was removed in vacuo and the residue was
chromatographed on SiO2 with hexane—ethyl acetate (10 : 1) as
the eluent to give adduct 2 (200 mg, 95%) as a colorless oil,
Rf 0.7 (hexane—ethyl acetate, 5 : 1). 1H NMR, δ: 7.35, 7.15
(both d, 4 H each, Ar); 6.45 (dd, X part of the ABX system, 1 H,
CH, J1 = 3.6 Hz, J2 = 8.5 Hz); 3.40 (m, AB part of the ABX
system, 2 H, CH2, JAB = 14 Hz, JAX = 3.6 Hz, JBX = 8.5 Hz);
2.35 (s, 3 H, Me—Ar); 2.05 (s, 3 H, MeCO). 13C NMR, δ:
169.8, 135.3, 131.6, 130.6, 129.6, 81.5, 42.2, 20.67, 20.1.
Found (%): C, 53.91; H, 5.47; Cl, 14.52; S, 13.05. C11H13Cl2S.
Calculated (%): C, 53.98; H, 5.35; Cl, 14.49; S, 13.10.
3 H, MeCO).
Methyl 3ꢀacetoxyꢀ2,2ꢀdimethylꢀ4ꢀ(4ꢀtolylthio)butanoate (7).
A. Ketene silyl acetal 6 (320 mg, 2.2 mmol) and a solution of
Et2AlCl—TMSOTf (2.52 mmol, 1 : 1) in hexane (2.5 mL) were
added at –15 °C to a stirred solution of adduct 2 (0.84 mmol) in
CH2Cl2 (5 mL) obtained in situ as described above. After 30 min,
the temperature was elevated to 20 °C and the reaction mixture
was left for 16 h and then poured into a stirred mixture of
saturated NaHCO3 and ether. The product from the aqueous
layer was additionally extracted with hexane (2×25 mL) and the
combined extracts were dried with CaCl2. The solvent was evapoꢀ
rated and the residue was chromatographed on SiO2 with hexꢀ
ane—ethyl acetate (10 : 1) as the eluent. The yield of compound
7 as a colorless oil was 122 mg (50%), Rf 0.3 (hexane—ethyl
acetate, 5 : 1). 1H NMR, δ: 7.30, 7.10 (both d, 4 H each, Ar);
5.40 (dd, X part of the ABX system, 1 H, CH, J1 = 3.6 Hz, J2 =
7.5 Hz); 3.60 (s, 3 H, MeOCO); 2.95 (m, AB part of the ABX
system, 2 H, CH2, JAB = 14 Hz, JAX = 3.6 Hz, JBX = 7.5 Hz);
2.30 (s, 3 H, Me—Ar); 2.00 (s, 3 H, MeCOO); 1.25 (s, 6 H,
Me2). Found (%): C, 61.83; H, 7.33; S, 10.23. C16H22O4S.
Calculated (%): C, 61.91; H, 7.14; S, 10.33.
B. Ketene silyl acetal 6 (160 mg, 1.1 mmol) was added to a
stirred solution of adduct 2 (0.84 mmol) in CH2Cl2 (5 mL)
obtained in situ as described above. The mixture was cooled to
–20 °C and AgOTf (260 mg, 1 mmol) was added in portions for
40 min. The precipitate of AgCl was formed. After 1 h, the
reaction mixture contained no starting adduct 2 (TLC data).
Conventional workup followed by column chromatography gave
adduct 7 in 55% yield. Products 7 from procedures A and B were
completely identical.
2ꢀChloroꢀ1ꢀ(4ꢀtolylthio)propanꢀ2ꢀyl acetate (4). Adduct 4
was obtained analogously from propenꢀ2ꢀyl acetate (3) (200 mg).
The adduct was not purified by chromatography because of its
instability. The solvent was removed to give adduct 4 (500 mg,
1,1ꢀDiacetoxyꢀ2ꢀ(4ꢀtolylthio)ethane (8). Silver triflate
(260 mg, 1 mmol) was added at 20 °C to a stirred solution of

Reactions of ArSCH2CH(R)ClOAc with Cꢀnucleophiles Russ.Chem.Bull., Int.Ed., Vol. 54, No. 3, March, 2005
747
adduct 2 (0.84 mmol) in CH2Cl2 (5 mL) obtained in situ as
described above. The reaction mixture was stirred for 30 min
and treated with a mixture of saturated NaHCO3 and ether. The
product from the aqueous layer was additionally extracted with
hexane (2×25 mL) and the combined organic extracts were dried
over CaCl2. The solvent was evaporated and the residue was
subjected to column chromatography with hexane—ethyl acꢀ
etate (10 : 1) as the eluent to give product 8 (70 mg, 62%) as a
this temperature for 12 h and then treated according to a stanꢀ
dard procedure. Purification by column chromatography gave
adduct 18 (220 mg, 80%) as a colorless oil. 1H NMR, δ: 7.30,
7.10 (both d, 4 H each, Ar); 4.78, 4.92 (both m, 1 H each,
CHOAc); 4.82, 4.72 (both s, =CH2); 3.53, 3.35 (both m, AB,
2 H, CH2, JAB = 1 Hz, JAB = 16 Hz); 2.80, 2.50 (both m, AB,
2 H, CH2, JAB = 16 Hz); 2.30 (s, 3 H, Me—Ar); 1.95 (s, 3 H,
MeCOO); 1.80 (s, 3 H, Me); 1.50 (s, 3 H, Me). Found (%):
C, 68.73; H, 8.21; S, 11.30. C16H22O2S. Calculated (%):
C, 69.02; H, 7.96; S, 11.52.
1
colorless oil, Rf 0.4 (hexane—ethyl acetate, 5 : 1). H NMR, δ:
7.30, 7.10 (both d, 4 H each, Ar); 6.85 (t, 1 H, CH, J = 5.5 Hz);
3.20 (d, 2 H, J = 5.5 Hz); 2.30 (s, 3 H, MeAr); 2.00 (s, 6 H,
MeCOO). 13C NMR, δ: 137.1, 131.1, 129.7, 89.1; 37.4, 20.9,
20.5. Found (%): C, 59.01; H, 6.3; S, 11.24. C13H16O4S. Calcuꢀ
lated (%): C, 58.19; H, 6.01; S, 11.95.
Methyl 3ꢀacetoxyꢀ4ꢀ(4ꢀtolylthio)butanoate (13) was obtained
from ketene silyl acetal 9 as a Cꢀnucleophile at 20 °C as deꢀ
scribed in procedure B for ester 7. The yield of adduct 13 was
55%. 1H NMR, δ: 7.35, 7.10 (both d, 4 H each, Ar); 5.30 (m,
1 H, CH); 3.70 (s, 3 H, MeOCO); 3.15 (m, SCH2, AB part of
This work was financially supported by the Russian
Foundation for Basic Research (Project Nos 00ꢀ03ꢀ32884
and 03ꢀ03ꢀ04001) and the German Research Society
(Deutsche Forschungsgemeinschaft, Grant MA673/19).
References
the ABX system, 2 H, CH2, JAB = 14 Hz, JAX = 6.7 Hz, JBX
=
1. (a) W. H. Mueller, Angew. Chem., Int. Ed. Engl., 1969, 8,
482; (b) M. G. Lin´kova and I. L. Knunyants, Usp. Khim.,
1977, 46, 548 [Russ. Chem. Rev., 1977, 46 (Engl. Transl.)];
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Double Bonded Functional Groups, Ed. S. Patai, Ch. 9, 1977.
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6.1 Hz); 2.75 (m, COCH2, AB part of the ABX system, 2 H,
CH2, JAB = 16 Hz, JAX = 7.9 Hz, JBX = 5.6 Hz); 2.30 (s, 3 H,
Me—Ar); 1.95 (s, 3 H, MeCOO). Found (%): C, 60.05; H, 6.63;
S, 11.23. C14H18O4S. Calculated (%): C, 59.55; H, 6.43; S, 11.36.
5,5ꢀDimethylꢀ4ꢀoxoꢀ1ꢀ(4ꢀtolylthio)hexanꢀ2ꢀyl acetate (14)
was obtained analogously at 0 °C from silyl vinyl ether 10 as a
Cꢀnucleophile. The yield of adduct 14 was 50%. 1H NMR, δ:
7.30, 7.10 (both d, 4 H each, Ar); 5.40 (quint, 1 H, CH, J =
6.1 Hz); 3.18 (d, SCH2, 2 H, CH2, J = 6.1 Hz); 2.92 (d, COCH2,
2 H, CH2, J = 6.1 Hz); 2.30 (s, 3 H, Me—Ar); 1.90 (s, 3 H,
MeCOO); 1.10 (s, 9 H, But). Found (%): C, 66.50; H, 7.93;
S, 10.23. C17H24O3S. Calculated (%): C, 66.20; H, 7.84; S, 10.39.
1ꢀ(4ꢀTolylthio)pentꢀ4ꢀenꢀ2ꢀyl acetate (15) was obtained
analogously at –15 °C from allyl(triꢀnꢀbutyl)stannane 11 as a
Cꢀnucleophile. The yield of adduct 15 was 80%. 1H NMR, δ:
7.30, 7.10 (both d, 4 H each, Ar); 5.85 (m, 1 H, CH=); 5.10 (m,
2 H, =CH2); 4.50 (m, 1 H, CH); 3.0 (m, 2 H, CH2); 2.35 (m,
2 H, CH2); 2.30 (s, 3 H, Me—Ar); 2.05 (s, 3 H, MeCOO).
Found (%): C, 67.01; H, 7.03; S, 12.45. C14H18O2S. Calcuꢀ
lated (%): C, 67.16; H, 7.25; S, 12.81.
8. (a) K. B. Sloan and S. A. Koch, J. Org. Chem., 1983, 48,
3777; (b) Yu. A. Zhdanov, S. M. Luk´yanov, and S. V.
Borodaev, Zh. Org. Khim., 1985, 21, 2067 [J. Org. Chem.,
1985, 21 (Engl. Transl.)]; (c) S. M. Luk´yanov and A. V.
Koblik, Usp. Khim., 1996, 65, 3 [Russ. Chem. Rev., 1996, 65
(Engl. Transl.)].
9. G. Hagen and H. Mayr, J. Am. Chem. Soc., 1991, 113, 4954.
10. P. Cazeau, F. Duboudin, F. Moulines, O. Babot, and
J. Dunogues, Tetrahedron, 1987, 43, 2075.
4ꢀMethylꢀ1ꢀ(4ꢀtolylthio)pentꢀ4ꢀenꢀ2ꢀyl acetate (16) was obꢀ
tained analogously at –15 °C from triꢀnꢀbutyl(methallyl)stanꢀ
nane 12 as a Cꢀnucleophile. The yield of adduct 16 was 90%.
1H NMR, δ: 7.30, 7.10 (both d, 4 H each, Ar); 5.15 (m, 1 H,
CHOAc); 4.82, 4.72 (both s, 2 H each, =CH2); 3.03 (m, 2 H,
CH2); 2.35 (m, 2 H, CH2); 2.30 (s, 3 H, Me—Ar); 1.95 (s, 3 H,
MeCOO); 1.70 (s, 3 H, Me). Calculated (%): C, 68.14, H, 7.62,
S, 12.13. C14H20O2S. Found (%): C, 69.01, H, 7.7; S, 12.10.
2,4ꢀDimethylꢀ1ꢀ(4ꢀtolylthio)pentꢀ4ꢀenꢀ2ꢀyl acetate (18).
Methallylstannane 12 and AgOTf (358 mg, 1.5 mmol) were
added at 0 °C to a solution of adduct 4 obtained in situ from
propenꢀ2ꢀyl acetate 3 (100 mg, 1 mmol) and pꢀTolSCl (158 mg,
1 mmol) in CH2Cl2 (5 mL). The reaction mixture was kept at
11. E. Kuhle, Synthesis, 1970, 561.
Received October 22, 2004