2008
M. Nasr-Esfahani et al.
General Procedure
Acidified wet silica gel was prepared by shaking silica gel (20 g, 70–230
mesh) with concentrated HCl (6 mL). The reagent was prepared by mix-
ing n-Bu4N+IO−4 (1 mmol, 0.433 g) with acidified, wet silica gel (3.0 g)
using a pestle and mortar until a fine, homogeneous, purple powder was
obtained. A mixture of thioamide (1 mmol) and n-Bu4N+IO4−/acidified,
wet SiO2 (1 mmol, 3.433 g) was ground with a pestle in a mortar until
the TLC showed complete disappearance of the thioamide, which re-
quired 2–11 min (Table I). Ethylacetate (2 × 10 mL) was added to the
reaction mixture, and after vigorous stirring was filtered through a sin-
tered glass funnel and the solvent was then evaporated under vacuum.
The solvent was evaporated, and the crude product was purified by
column chromatography on silica gel using ethyl acetate as an eluent.
The pure products were obtained in 91–97% yields.
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