Lithium Chloride → 5-ethyl-7-oxo-6,7-dihydro-5H-thieno[3,2-b]pyridine-4-carboxylic acid isopropyl ester

Participants

Reaction Conditions

Reaction Steps

Add lithium chloride (0.162 g, 3.83 mmol) in one portion to a mixture of 5-ethyl-7-oxo-6,7-dihydro-5H-thieno[3,2-b]pyridine-4,6-dicarboxylic acid 6-ethyl ester 4-isopropyl ester (0.520 g, 1.53 mmol) in dimethylsulfoxide (15 ml) and water (2 drops). Heat the mixture at 160° C. for 4 h. Cool the reaction to room temperature and partition between ethyl acetate (50 ml) and brine (50 ml). Separate the organic layer and wash with brine (3×50 ml). Dry the organic portion over sodium sulfate, filter and concentrate. Purify using silica gel column chromatography (gradient eluent, 0-15% ethyl acetate in hexane) to give 5-ethyl-7-oxo-6,7-dihydro-5H-thieno[3,2-b]pyridine-4-carboxylic acid isopropyl ester (0.236 g, 58% for two steps) as an oil. MS (ES+): 268 (M+H).

Provenance & Evidence