3464 J . Org. Chem., Vol. 65, No. 11, 2000
Xu et al.
ining the NMR spectrum, several compounds could be identi-
fied based on their chemical shifts: mainly methyl iodide, 5,
and TMSX, along with small amounts of DMS and di-
iodomethane. Also, a small peak at 9.62 ppm indicated the
formation of the intermediate methylmethylenesulfonium
cation. There were also some other unidentified materials. This
experiment was repeated several times, and the NMR spectra
were not consistent each time.
When excess of sodium thiophenoxide was added to the
reaction mixture, the reaction gave mainly phenylthiomethyl
methyl sulfide, phenyl methyl sulfide, and dimethyl sulfide
along with some diphenylthiomethane.
P h en ylth iom eth yl Meth yl Su lfid e. Syn th esis of Au -
th en tic P r od u ct. Into a 25 mL round-bottom flask equipped
with stirrer, thermometer, and reflux condenser was added a
solution containing 0.82 g of sodium methoxide (15.2 mmol)
in 10 mL of absolute methanol. While maintaining the solution
at 25-30 °C, 1.67 g (15.2 mmol) of thiophenol in 4 mL of
absolute methanol was added. Thereto, at 25 °C, 1.47 (15.2
mmol) of chloromethyl methyl sulfide in 4 mL of absolute
methanol was added to reaction mixture with stirring. The
reaction mixture was warmed to 35 °C and stirred for 3 h.
The solvent was evaporated, in vacuo, and then hexane was
added. The hexane solution was washed with brine, and after
removal of solvent, the residue was purified by column
chromatography (hexane) to obtain a liquid 2.3 g (88%): 1H
NMR (CDCl3), δ 1.24 (s, 3H), 4.01 (s, 2H), 7.21-7.40 (m, 3H),
7.31 (d, J ) 6.6 Hz, 2H); 13C NMR, δ 15.33, 40.56, 127.12,
129.11, 130.79, 135.31; HRMS (EI) Calcd for C8H10S2: 170.0224;
found: 170.0223.
P h en ylt h iom et h yld im et h ylsu lfon iu m Tet r a flu ob or -
a te, 9. Into a suspension of trimethyloxonium tetrafluorobo-
rate (0.35 g, 2.4 mmol) in methylene chloride (10 mL) was
added phenylthiomethyl methyl sulfide (0.4 g, 2.4 mmol)
under dry nitrogen at -78 °C. The reaction mixture was
warmed to room temperature and stirred for 3 h. The reaction
mixture separated into two layers. The solvent was decanted,
and the residue was recrystallized from ethyl acetate to give
a white solid 0.42 g (70%): 1H NMR (DMSO-d6), δ 2.79 (s, 6H),
4.68 (s, 2H), 7.42-7.48 (m, 3H), 7.56-7.65 (m, 2H); 13C NMR,
δ 24.09, 46.69, 128.57, 129.72, 130.83, 131.08; LSI MS POS
calcd for C9H13S2+: 185.0459; found: 185.0460.
A 2H NMR spectrum of the reaction mixture showed a triplet
at 3.11 ppm with the coupling constant of 2.1 Hz, indicating
formation of (CH3)2S+CH2D salt. Using toluene as an quantita-
tive internal standard for the protons and CD2Cl2 as a
quantitative internal standard for the deuterium of (CH3)2S+-
CH2D, a ratio of 27 was obtained for H vs D in this obtained
TMSX. This indicates a 31% incorporation of deuterium into
TMSX by deuterium atom abstraction from CD3CN.
Rea ction of 4b w ith Iod id e Ion (a t 70 °C). A similar
1
reaction mixture was heated at 70 °C for 5 h, and the H and
13C NMR spectra revealed the major (60%) product to be
TMSX.
Rea ction of 4b w ith DMS a t 60 °C. 4b (0.52 g, 1.8 mmol)
was dissolved in acetonitrile (5 mL). DMS (0.3 g, 4.8 mmol)
was added, and the reaction mixture was heated at 60 °C
overnight. The solvent was evaporated, and the residue was
recrystallized from ethanol to obtain white solid 0.30 g (94%).
The 1H and 13C NMR spectra revealed that the solid was
TMSX.
Rea ction of 4b w ith DMS (a t r oom tem p er a tu r e). A
similar mixture was prepared and allowed to stand at room
temperature. The 1H NMR spectrum was immediately re-
corded and showed only starting materials. The reaction
progress was observed for 2 days. It was observed that the 4b
had been consumed after 2 days, with the reaction mixture
showing the presence of several products including TMSX, 5,
methyl iodide, and methylthiomethyldimethylsulfonium salt,
6,5 with the ratio of theses compounds being 12:2:2:6.
Rea ction of 4c w ith DMS. In an NMR tube, 4c (20 mg,
0.1 mmoml) was dissolved in acetonitrile-d3 (0.7 mL), and the
tube was sealed with a rubber septum. DMS (6.2 mg, 0.1
mmol) was added into the reaction mixture by a syringe. The
1H NMR spectrum was recorded and showed that only starting
materials were present. After standing at room temperature
for 2 days, the 1H NMR showed that no reaction had occurred.
The reaction mixture was heated at 80 °C, and the reaction
progress was observed for 3 days by 1H NMR spectroscopy.
The 4c had been consumed after 30 h, with the reaction
mixture showing the presence of several products, including
TMSX, chloromethyl methyl sulfide, and methylthiometh-
yldimethylsulfonium salt. After 3 days, the major product was
TMSX (>90%), with a small amount of chloromethyl methyl
sulfide, and methylthiomethyldimethylsulfonium compound
still being present.
Rea ction of 9 w ith Sod iu m Th iop h en oxid e. To demon-
strate the secondary reaction chemistry of 9 with thiophenox-
ide, the following reaction was studied. In a NMR tube, 9
(0.0272 g, 0.1 mmol) and sodium thiophenoxide (0.0132 g, 0.1
mmol) were dissolved in DMSO-d6 (0.7 mL). After 10 min, the
1H NMR spectrum showed that starting material was gone.
The reaction mixture contained several products, including
phenylthiomethyl methyl sulfide, phenyl methyl sulfide, bis(phe-
nylthio)methane, and DMS. The ratio of these compounds was
2.9:2.9:1:1.
Rea ction of TMSI w ith Sod iu m Th iop h en oxid e. In an
NMR tube, TMSI (0.0204 g, 0.1 mmol) and sodium thiophe-
noxide (0.0132 g, 0.1 mmol) were dissolved in DMSO-d6 (0.7
1
mL). After 10 min, the H NMR spectrum showed that 10% of
starting material had been consumed. After overnight, the
reaction quantitatively gave phenyl methyl sulfide and DMS.
F lu or om eth yld im eth ylsu lfon iu m Tetr a flu or obor a te,
4d . The following procedure for the preparation was modified
based on a literature procedure.18 In a three-neck round-
bottomed flask, in which one of necks was connected to a trap
cooled to -78 °C, a solution of dimethyl sulfoxide (0.4 g, 5
mmol) in methylene chloride (5 mL) was added. To the above
solution was added DAST (1 g, 6.2 mmol) under nitrogen, and
the mixture was stirred at room temperature. The progress
of the reaction was monitored by the appearance in the 1H
NMR of the CH2F product signal (doublet, J HF ) 53.2 Hz)
centered at δ 5.41. After 28 h, the NMR spectrum showed the
completion of reaction (disappearance of DMSO), but there was
nothing in the trap. The products remained in solution, as
indicated by the NMR spectrum which indicated the presence
of the desired product: fluoromethyl methyl sulfide: 1H NMR
(CDCl3), δ 2.25 (d, J ) 2.7 Hz, 3H), 5.41 (d, J ) 53.2 Hz, 2H);
19F NMR, δ -188.56 (t, J ) 53.2 Hz, 1F).
Rea ction of 4b w ith Sod iu m Th iop h en oxid e. At -78
°C. In an NMR tube, 4b (0.0361 g, 0.12 mmol) was dissolved
in 3:1 of CDCl3 and DMSO-d6 (0.5 mL). The NMR tube was
cooled to -78 °C with dry ice/acetone. After 10 min, a solution
of sodium thiophenoxide (0.0164 g, 0.12 mmol) in 3:1 of CDCl3/
DMSO-d6 (0.5 mL) was added to the NMR tube at -78 °C.
The NMR tube was shaken to mix the two solutions, and it
1
was maintained at -78 °C for 30 min. The H NMR spectrum
was then taken, and it showed the reaction to be finished. The
main products were phenylthiomethyldimethylsulfonium salt,
9, for which the NMR ratio of methylene group (5.08 ppm) to
dimethyl group (2.91 ppm) was 1 to 3, and TMSX (ratio of
products ) 4.9:1) (92%). The other 8% of the products were
the secondary reaction products that are seen to dominate
when the reaction is run at 0 °C or higher.
Room -Tem p er a tu r e Rea ction . A similar reaction mixture
1
The solution was distilled into a flask containing trimethyl-
oxonium tetrafluoroborate (0.5 g), and the resulting mixture
was sealed and stirred overnight at room temperature. The
solvents were evaporated, and the residue was recrystallized
was prepared, and after 10 min, the H NMR spectrum of the
mixture showed that all 4b was gone. The reaction mixture
contained several products, including 9, along with phenylthi-
omethyl methyl sulfide (1:3 of CH2 (4.19 ppm): CH3 (2.46
ppm)), diphenylthiomethane (4.64 ppm), DMS (2.04 ppm),
TMSX (2.90 ppm), and phenyl methyl sulfide (2.15 ppm). The
ratio of these compounds was 4.7:2:1:1:0.5:1.
(18) McCarthy, J . R.; Peet, N. P.; Le Tourneau, M. E.; Ingasekaran,
M. J . J . Am. Chem. Soc. 1985, 107, 735.