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M. K. W. Choi, P. H. Toy / Tetrahedron 60 (2004) 2875–2879
NaHCO3 (250 mL) and brine (250 mL). The organic layer
was dried over MgSO4, filtered and concentrated in vacuo.
The crude product was purified by silica gel chromato-
graphy (5% EtOAc/hexanes) to afford 1 as a clear, colorless
liquid (16.0 g, 106.5 mmol, 70%). 1H NMR (400 MHz,
CDCl3) d 2.45 (s, 3H), 5.21 (dd, 1H, J¼10.9, 0.9 Hz), 5.70
(dd, 1H, J¼17.6, 0.9 Hz), 6.68 (dd, 1H, J¼17.6, 10.9 Hz),
7.17–7.40 (m, 4H). 13C NMR (100 MHz, CDCl3) d 15.7,
113.1, 126.6 (4C), 134.5, 136.2, 138.0. HR EI-MS: calcd for
C9H10S, 150.0503; found, 150.0500.
dried over MgSO4, filtered and concentrated in vacuo. The
crude residue was filtered through a plug of silica gel to
provide the essentially pure epoxide product (Table 1).
4.3. Procedure for regeneration of polymer 3
The polymer mixture (2 with 3, ca. 1.0 g) recovered from
the epoxide synthesis reaction was treated with MeOTf
(1.5 g, 8.9 mmol) in CH2Cl2 (20 mL) and stirred for 24 h at
rt. The resin was recovered and washed sequentially with
dichloromethane, methanol, diethyl ether and hexanes. The
shrunken beads 3 were dried in vacuo and reused in the
epoxidation reaction. The same sample of 3 was used in all 5
cycles reported in Table 2 using this procedure.
4.1.2. JandaJele-SMe (2). A solution of acacia gum
(6.0 g) and NaCl (3.8 g) in warm deionized water (45 8C,
150 mL) was placed in a 150 mL flanged reaction vessel
equipped with a mechanical stirrer and deoxygenated by
purging with N2 for 2 h.21 A solution of 1 (10.0 g,
6.7 mmol), cross-linker (0.4 g, 1.5 mmol) and AIBN
(0.2 g, 1.3 mmol) in chlorobenzene (10 mL) was injected
into the rapidly stirred aqueous solution. The mixture was
heated at 85 8C for 20 h. The crude polymer was collected
and washed with hot water (3£100 mL) and then placed in a
Soxhlet extractor and washed with THF for 1 day. The
beads were recovered, washed with methanol (250 mL),
diethyl ether (250 mL), and hexanes (250 mL). The
shrunken beads 2 (9.0 g, 90%) were dried in vacuo.
Elemental analysis was used to determine the sulfur content
(18.9%) and thus the loading level of 5.9 mmol S/g of 2.
4.4. General procedure for alcohol oxidation
A suspension of 4 (1.0 g, 4.8 mmol) in anhydrous CH2Cl2
(30 mL) was cooled to 270 8C and oxalyl chloride (0.6 g,
4.4 mmol) was added dropwise. After 30 min, a solution of
the alcohol (1.2 mmol) in anhydrous CH2Cl2 was added.
The mixture was stirred at low temperature for 1 h and then
triethylamine (0.7 g, 7.2 mmol) was added. The solution is
kept at 240 8C for 1 h more and then allowed to warm to rt.
The suspension was then filtered and the resin was washed
with addition CH2Cl2 (3£10 mL). The combined filtrate was
concentrated in vacuo and the crude residue was filtered
through a plug of silica gel to provide the essentially pure
oxidation product (Table 3).
4.1.3. JandaJele-S(Me)2OTf (3). To a magnetically
stirred suspension of 2 (3.0 g, 17.7 mmol) in CH2Cl2
(30 mL) at rt was added MeOTf (4.4 g, 27.0 mmol). Stirring
was continued for 24 h at rt, at which time the resin was
filtered off, and washed sequentially with dichloromethane,
methanol, diethyl ether, and hexanes. The shrunken beads 3
(6.0 g) were dried in vacuo. Elemental analysis was used to
determine the sulfur content (18.3%) and thus the loading
level of 2.9 mmol S/g of 3.
4.5. Procedure for regeneration of polymer 4
The polymer mixture (2 with 4, ca. 1.0 g) recovered from
the oxidation reaction was treated with 70% TBHP (3.1 g,
24.0 mmol) and p-TSA (0.9 g, 4.8 mmol) in CH2Cl2
(20 mL) and stirred at rt for 24 h. The beads were recovered,
and washed sequentially with dichloromethane, methanol,
diethyl ether and hexanes. The shrunken beads 4 were dried
in vacuo and reused in the oxidation reaction. The same
sample of 4 was used in all 5 cycles reported in Table 4
using this procedure.
4.1.4. JandaJele-S(O)Me (4). To a magnetically stirred
suspension of 2 (5.0 g, 29.5 mmol) in CH2Cl2 (40 mL) at rt
was added 70% TBHP (19.3 g, 150.0 mmol) and p-TSA
(5.6 g, 30.0 mmol). Stirring was continued for 24 h at rt, at
which time the resin was filtered off and washed
sequentially with dichloromethane, methanol, diethyl
ether, and hexanes. The shrunken beads 4 (5.5 g) were
dried in vacuo. Elemental analysis was used to determine
the sulfur content (15.4%) and thus the loading level of
4.8 mmol S/g of 4. Previous reports using this oxidation
system indicate that oxidation of the sulfide stops at the
sulfoxide oxidation state and that no sulfone is formed.5,18c
Acknowledgements
This research was supported financially by the University of
Hong Kong, and the Research Grants Council of the Hong
Kong Special Administrative Region, P. R. of China
(Project No. HKU 7112/02P). We also thank Mr. Bob
Wandler of the Aldrich Chemical Co. for supplying many of
the reagents used in this study.
4.2. General procedure for epoxide synthesis
A solution of the carbonyl compound (1.0 mmol) in
anhydrous DMSO (4 mL) and anhydrous THF (1 mL) was
added to a mixture of 3 (1.0 g, 2.9 mmol) and 60% NaH
(0.12 g, 3.0 mmol) in anhydrous THF (2 mL) that was
stirring at 0 8C. The mixture was slowly warmed to rt after
the reaction was complete. The suspension was then filtered
and the resin was washed with addition diethyl ether
(3£10 mL). The combined filtrate was treated with water
(40 mL) and extracted with diethyl ether (3£20 mL). The
combined organic layer was washed with brine (30 mL),
References and notes
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R. I.; Taylor, S. J. J. Chem. Soc., Perkin Trans. 1 2000,
3815–4195. (b) Clapham, B.; Reger, T. S.; Janda, K. D.
Tetrahedron 2001, 57, 4637–4662.
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3217–3274. (b) McNamara, C. A.; Dixon, M. J.; Bradley, M.