Hydrochloric Acid → 6-methyl-4,5,6,7-tetrahydrobenzo[b]thiophene-2-carboxylic acid

Participants

Reaction Steps

To a solution of 704 mg of 6-methyl-4,5,6,7-tetrahydro-benzo[b]thiophene-2-carboxylic acid methyl ester (obtained in step b) in a mixture of THF (5ml) and methanol (2 ml) were added 8.37 ml of 1N LiOH and the reaction mixture was stirred at RT for 16 h. Then the pH was adjusted to 2 by addition of 2N HCl and the suspension was extracted with ethyl acetate. The combined organic extracts were washed with brine, dried (MgSO4) and concentrated. The remaining residue was then purified by crystallization from hot dichloromethane to give 574 mg (87%) of 6-methyl-4,5,6,7-tetrahydro-benzo[b]thiophene-2-carboxylic acid as brown solid. MS (ISP) 195.1 (M−H)−.

Provenance & Evidence