2342
S. K. Singh and K. N. Singh
were recorded on a JASCO FT/IR-5300 spectrophotometer. NMR spec-
tra were run on a JEOL AL300 FTNMR spectrometer; chemical shifts
are given in δ ppm, relative to TMS as the internal reference. All the
products were purified by column chromatography.
REACTION OF IN SITU GENERATED
TETRAETHYLAMMONIUM SUPEROXIDE WITH
1,3-OXATHIOLANES (1a–1l): GENERAL PROCEDURE
A mixture of potassium superoxide (1.13 g, 16 mmol) and tetraethylam-
monium bromide (1.68 g, 8 mmol) (weight under a nitrogen atmosphere
using an atmosbag) in dry DMF (25 mL) was stirred for 15 min, and
then the substrate 1,3-oxathiolane (1a-1l) (8 mmol) was added. After
the reaction was over (1.5 to 3 h) as indicated by TLC, a cold brine so-
lution (10 mL) was introduced to decompose the unreacted potassium
superoxide, followed by the addition of saturated sodium hydrogen car-
bonate solution (10 mL). The reaction mixture was extracted with di-
ethyl ether (3 × 15 mL). The combined organic extract was dried over
anhydrous Na2SO4, filtered, and evaporated to give the crude product
(
2a-2l), which was purified by column chromatography on silica gel us-
ing n-hexane:ethyl acetate (9:1) as an eluent. The aqueous phase was
acidified with hydrochloric acid and extracted with diethyl ether (3 ×
10 mL) to isolate the acidic product.
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