4972 J. Am. Chem. Soc., Vol. 123, No. 21, 2001
Toutchkine et al.
1
Experimental Section
2 3
Ethyl γ-Methylsulfonylcrotonate (5a-SO ). H NMR (CDCl ) δ
1
.30 (t, J ) 7.3 Hz, 3H), 2.92 (s, 3H), 3.87 (d, J ) 7.9 Hz, 2H), 4.24
(q, J ) 7.3 Hz, 2H), 6.16 (d, J ) 15.6 Hz, 1H), 6.95 (dt, J ) 15.6, 7.9
General Aspects. A HP-5 (30 m × 0.25 mm × 0.25 µm (length ×
inside diameter × film thickness)) capillary column was used for GC/
MS data collection and a 5% diphenyl-95% dimethyl polysiloxane
Hz, 1H).
1
Methyl Thiomethyl Acetate (5c). H NMR (CDCl ) δ 2.22 (s, 3H),
3
3.21 (s, 2H), 3.75 (s, 3H). 13C NMR (CDCl ) δ 16.6, 35.7, 52.6, 171.0.
(
30 m × 0.32 mm × 1.0 µm (length × inside diameter × film
thickness)) or a HP-1 cross linked methyl silicon (30 m × 0.53 mm ×
.5 µm (length × inside diameter × film thickness)) fused silica column
was used for analytical GC data collection. H and C NMR spectra
of CDCl or C solutions of substrates and reaction mixtures were
recorded at 400.13 MHz on a Bruker Avance DRX-400 spectrometer.
The peaks corresponding to the residual protons of CDCl (7.27 ppm)
or C (7.16 ppm) were used as the internal reference. The triplet at
7.23 (CDCl
3
1
Methyl Methylsulfinyl Acetate (5c-SO). H NMR (CDCl ) δ 2.76
(s, 3H), 3.70 (d, J ) 14 Hz, 1H), 3.74 (d, J ) 14 Hz, 1H). C NMR
3
1
3
1
1
13
(CDCl ) δ 39.7, 53.1, 57.8, 165.6.
3
1
3
6
D
6
Methyl Hydroxymethylthioacetate (5c-OH). H NMR (CDCl ) δ
3
2.18 (s, 3H), 3.86 (s, 3H), 5.23 (d, J ) 5.0 Hz, 1H). 13C NMR (CDCl
3
)
3
δ 11.7, 53.3, 73.8, 171.7.
6
D
6
Benzyl Methyl Sulfide (5d). Benzyl mercaptan (5.4 g, 43 mmol)
was converted to the sodium thiolate by stirring with 1 equiv of sodium
methoxide in 30 mL of methanol under a nitrogen atmosphere.
Iodomethane (6.2 g, 44 mmol) was added dropwise to the methanol
solution of the thiolate and the reaction mixture was refluxed overnight.
) was used as the reference for the 1 C NMR spectra.
3
7
3
Combustion analyses were obtained from Atlantic Microlab in Norcross,
Georgia. Anhydrous diethyl ether and tetrahydrofuran were distilled
from sodium benzophenone ketyl.
The product was obtained in 82% yield after purification by distillation.
The endoperoxide of 1,4-dimethylnaphthalene was prepared by the
1
3
0
H NMR (CDCl
Benzyl Methyl Sulfoxide (5d-SO). H NMR (CDCl
3
) δ 1.99 (s, 3H), 3.68 (s, 2H), 7.23-7.34 (m, 5H).
method of Wasserman and Larsen. 1,1-Dichloroacetone, thiophenol,
thionyl chloride, and iodomethane were obtained from Acros Chemical
and used without further purification. 1-Bromo-2,2,2-trifluoroethane,
MCBPA, dimethylamine, ethyl trans-crotonate, N-bromosuccinimide,
methanethiol, and benzyl mercaptan were obtained from Aldrich
Chemical Co. and used without further purification. Anhydrous MgSO ,
4
pyridine (HPLC grade), and potassium carbonate were obtained from
Spectrum and used without further purification.
1
3
) δ 2.46 (s,
3
H), 3.93 (d, J ) 12.8 Hz, 1H), 4.07 (d, J ) 12.8 Hz, 1H), 7.23-7.34
(m, 5H).
1
Benzyl Methyl Sulfone (5d-SO
2
). H NMR (CDCl
3
) δ 2.75 (s, 3H),
4
7
.25 (s, 2H), 7.23-7.34 (m, 5H).
Benzyl Ethyl Sulfoxide (5e-SO). H NMR (C
.5 Hz, 3H), 1.73 (dq, J ) 13.1, 7.5 Hz, 1H), 2.03 (dq, J ) 13.1, 7.5
1
6 6
D
) δ 0.91 (t, J )
Hz, 1H), 3.40 (d, J ) 12.8 Hz, 1H), 3.48 (d, J ) 12.8 Hz, 1H), 6.95-
7
One-hundred gram bottle(s) of chloroform-d (Cambridge Isotope
Laboratories) were extracted with 40 mL of saturated aqueous sodium
bicarbonate, dried with magnesium sulfate, and stored over 4 Å
molecular sieves under nitrogen at 10 °C.
.11 (m, 5H).
1
2 3
Benzyl Ethyl Sulfone (5e-SO ). H NMR (CDCl ) δ 1.35 (t, J )
.5 Hz, 3H), 2.85 (q, J ) 7.5 Hz, 2H), 4.22 (s, 2H), 7.4 (s, 5H).
7
1
Ethylthioethylmethyl Sulfide (5f). H NMR (CDCl
J ) 7.4 Hz, 6H), 2.65 (q, J ) 7.4 Hz, 4H), 3.69 (s, 2H).
3
) δ 1.26 (t,
General Procedure for Sulfide Photooxidation. Photooxidation
-
4
reaction mixtures 0.05-0.08 M in sulfide and 2.5 × 10 M in
tetraphenylporphyrin (TPP) were prepared in CDCl in 5 mL volumetric
flasks. Each mixture was then treated with 0.25 g of Na CO and
1
Ethylthioethylmethyl Sulfoxide (5f-SO). H NMR (CDCl
3
) δ 1.26
3
(
(
1
t, J ) 7.5 Hz, 3H), 1.31 (t, J ) 7.5 Hz, 3H), 2.67-2.79 (m, 3H), 2.94
dq, J ) 13.3, 7.6 Hz, 1H), 3.64 (d, J ) 13.7 Hz, 1H), 3.68 (d, J )
2
3
allowed to stir for 10 min in the dark. The solutions were then filtered
and divided into 1 mL portions for irradiation in 100 mL test tubes.
The samples were presaturated with oxygen for 2 min and then
irradiated under a constant stream of oxygen with a 600 W tungsten
3.7 Hz, 1H).
1
2 3
Ethylthioethylmethyl Sulfone (5f-SO ). H NMR (CDCl ) δ 1.29
(
3
1
t, J ) 7.5 Hz, 3H), 1.38 (t, J ) 7.5 Hz, 3H), 2.90 (q, J ) 7.5 Hz, 2H),
13
.21 (q, J ) 7.5 Hz, 2H), 3.82 (s, 2H). C NMR (CDCl ) δ 6.72,
3
2
lamp at 23 °C through 1 cm of a 12 M NaNO filter solution. The
4.12, 27.09, 44.23, 51.28.
Ethyl Thioethyl Acetate (5g). H NMR (CDCl
irradiation time is chosen to keep the conversion of starting material
to less than or equal to 20%. After the photooxidations the samples
1
3
) δ 1.27 (t, J ) 7.3
Hz, 3H), 1.28 (t, J ) 7.1 Hz, 3H), 2.65 (q, J ) 7.3 Hz, 2H), 3.17 (s,
H), 4.18 (q, J ) 7.1 Hz, 2H).
Ethyl Ethylsulfinyl Acetate (5g-SO). H NMR (CDCl
1
are kept in the dark and analyzed by H NMR as quickly as possible
2
(
5-10 min after photooxidation). The product ratios represent the
averages from 3 to 4 independently photooxidized samples.
1
3
) δ 1.28 (t,
J ) 7.2 Hz, 3H), 1.36 (t, J ) 7.4 Hz, 3H), 2.82 (dq, J ) 7.6, 13.6 Hz,
1H), 2.91 (dq, J ) 13.6, 7.5 Hz, 1H), 3.64 (s, 2H), 4.22(q, J ) 7.2 Hz,
Ethyl γ-Methylthiocrotonate (5a). Ethyl trans-crotonate (10 g, 88
mmol) was stirred at reflux with 1 equiv of N-bromosuccinimide (NBS;
5 g) and 0.12 g of benzoylperoxide in 54 mL of carbon tetrachloride.
2H).
1
1
Ethyl Ethylsulfonyl Acetate (5g-SO
2
). H NMR (CDCl
3
) δ 1.31
The extent of bromination was monitored by gas chromatography.
Additional NBS was added as necessary to bring the yield of the allylic
bromide up to greater than 80%. The ethyl γ-bromo-trans-crotonate
product was then purified by distillation. A portion of the allylic bromide
(t, J ) 7.2 Hz, 3H), 1.43 (t, J ) 7.4 Hz, 3H), 3.28 (q, J ) 7.4 Hz, 2H),
3.94 (s, 2H), 4.26 (q, J ) 7.2 Hz, 2H).
1
Methyl 2-Thioethylpropionate (5h). H NMR (CDCl
3
) δ 1.21 (t,
J ) 7.4 Hz, 3H), 1.41 (d, J ) 7.1 Hz, 3H), 2.58 (dq, J ) 12.4, 7.3 Hz,
1H), 2.62 (dq, J ) 12.4, 7.4 Hz, 1H), 3.39 (q, J ) 7.1 Hz, 1H), 3.70
(s, 3H).
(4.4 g; 23 mmol) was then added to 20 mL of diethyl ether and cooled
to -78 °C. This solution was then treated with 0.9 equiv (1.0 g) of
methanethiol and allowed to warm slowly to 0 °C. The reaction mixture
was then treated with 0.9 equiv of triethylamine, stirred for 2 h, and
finally heated at reflux for 4 h. The reaction mixture was worked up
by washing with 30 mL of diethyl ether, drying with MgSO , and
4
removal of diethyl ether by rotorary evaporation. Final purification was
1
Methyl 2-Ethylsulfinylpropionate (5h-SO). Two diastereomers. H
NMR (CDCl ) δ 1.23 (t, J ) 7.5 Hz, 3H), 1.24 (t, J ) 7.5 Hz, 3H),
3
1.39 (d, J ) 7.1 Hz, 3H), 1.41 (d, J ) 7.3 Hz, 3H), 2.62-2.70 (m,
4H), 3.45 (q, J ) 7.1 Hz, 1H), 3.59 (q, J ) 7.3 Hz, 1H), 3.65 (s, 3H),
3.66 (s, 3H)). 13C NMR (CDCl
) δ 6.79, 7.21, 9.50, 10.32, 42.73, 44.53,
3
accomplished by radial chromatography (hexane/ethyl acetate 200/1)
52.59, 52.68, 58.44, 59.37, 168.39, 169.34.
Methyl 2-Ethylsulfonylpropionate (5hSO ). H NMR (CDCl ) δ
2 3
1
1
to give a 31% yield of product. H NMR (CDCl
3
) δ 1.3 (t, J ) 7.1 Hz,
3
H), 2.03 (s, 3H), 3.19 (dd, J ) 7.5, 1.1 Hz, 2H), 4.2 (q, J ) 7.1 Hz,
1.42 (t, J ) 7.4 Hz, 3H), 1.41 (d, J ) 7.1 Hz, 3H), 3.17 (dq, J ) 7.5,
13.9 Hz, 1H), 3.25 (dq, J ) 7.5, 13.8 Hz, 1H), 3.81 (s, 3H), 3.94 (q,
2
H), 5.8(d, J ) 15.5 Hz, 1H), 6.86 (dt, J ) 15.5, 7.5 Hz, 1H).
J ) 7.3 Hz, 1H). 13C NMR (CDCl
) δ 6.11, 10.65, 45.91, 53.53, 62.18,
1
3
Ethyl γ-Methylsulfinylcrotonate (5a-SO). H NMR (CDCl
3
) δ 1.30
1
67.34.
Pyruvaldehyde Diethylthioacetal (5i). Fifty millimoles of 1,1-
(t, J ) 7.1 Hz, 3H), 2.61 (s, 3H), 3.55 (ddd, J ) 12.9, 7.9, 1.1 Hz,
1
6
H), 3.62 (ddd, J ) 12.9, 7.9, 1.1 Hz, 1H), 4.22 (q, J ) 7.1 Hz, 2H),
.11(bd, J ) 15.6 Hz, 1H), 6.95 (dt, J ) 15.6, 7.9 Hz, 1H).
dichloroacetone was added dropwise to a 50 mL slurry of dried acetone
containing 5 g of powdered potassium carbonate and 120 mmol of ethyl
mercaptan. The reaction mixture was allowed to stir at room temperature
for 24 h and the dithioacetal isolated (6.8 g, 93% yield) by vacuum
(
30) Wasserman, H. H.; Larsen, D. L. J. Chem. Soc., Chem. Commun.
972, 253-254.
31) Hansch, C.; Leo, A.; Taft, R. W. Chem. ReV. 1991, 91, 165-195.
1
1
(
distillation as a slightly yellow oil (bp 138-139 °C; 0.7 mmHg). H