Acetic Anhydride → 4-(Carbamoylamino)-4,5,6,7-tetrahydro-1-benzothiophen-7-yl acetate

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Reaction Steps

Two g (9.43 mm) of 4,5,6,7-tetrahydro-7-hydroxybenzo[b]thien-4-ylurea is stirred for 2 days at room temperature with acetic anhydride (5 ml) and pyridine (10 ml). The excess reagents are removed in vacuo, the resulting gum dissolved in methylene chloride (50 ml), the solution washed with water (50 ml), the water wash counter extracted with methylene chloride (25 ml), the combined methylene chloride layers dried with sodium sulfate and evaporated. The resulting gum is treated with ethyl acetate (≈5 ml) to afford a first crop (1.15 g, 48% Y) of the title compound, m.p. 168° C-170° C, dec. and a second crop (0.58 g, 24% Y) m.p. 166° C-172° C, dec. The analytical sample crystallized from ethyl acetate has m.p. 165° C-168° C dec. The isomeric compound prepared in the same manner melts at 182° C-184° C.

Provenance & Evidence