Methanamine, N-methoxy-, hydrochloride (1:1) → 4,5,6,7-tetrahydro-N-methoxy-N,5,5-trimethyl-benzo[c]thiophene-1-carboxamide

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Reaction Steps

To a solution of 5,5-dimethyl-4,5,6,7-tetrahydro-benzo[c]thiophene-1-carboxylic acid (20 g, 95 mmol) in DMSO (150 mL) is added N,O-dimethylhydroxylamine hydrochloride (12.06 g, 124 mmol) and DIPEA (65 mL, 380 mmol), followed by TBTU (33.59 g, 105 mmol, dissolved in DMF (70 mL)). The reaction mixture is stirred at rt for 2 h before it is poured into water/ice and extracted twice with diethyl ether (2×100 mL). The organic extracts are washed with sat. aq. NaHCO3 solution, 10% aq. citric acid solution and brine, dried over Na2SO4, filtered, evaporated and dried to give 5,5-dimethyl-4,5,6,7-tetrahydro-benzo[c]thiophene-1-carboxylic acid methoxy-methyl-amide (23 g) as a brown oil; LC-MS: tR=1.01 min, [M+1]=254.14.

Provenance & Evidence