Diethyl Ether → Dimethyl 4-aminothiophene-2,3-dicarboxylate Hydrochloride

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Reaction Steps

3-Oxo-4,5-bismethoxycarbonyltetrahydrothiophene (2.65 g) was dissolved in propionitrile (5 ml) and hydroxylamine hydrochloride (1 g) was added. The mixture was heated under reflux on the steam bath for 11/2 hours by which time it was almost solid. Ether was added to the cooled mixture and the title compound was filtered off. Yield 2.37 g (77.5%) M.P.166°-169° dec. 3-Amino-4,5-bismethoxycarbonylthiophene was liberated from the title compound by treatment with aqueous ammonia followed by bulk distillation (220° C., 0.1 mm Hg) and exhibited 'H n.m.r. δ (CDCl3) 6.40 (1H,s), 4.40 (2H, brs), 3.90, 3.94 (2×3H,s).

Provenance & Evidence