Methane → 6-Methyl-1-benzothiophene-2-carboxylic acid

Participants

Reaction Steps

A suspension of palladium on 5% wet charcoal (50% water) (1.065 g) and ammonium formate (2.52 g) in methanol (30 ml) is stirred for 20 minutes in an inert atmosphere; a solution of 2.52 g of ammonium formate in 5 ml of water and a solution consisting of 2.26 g of 3-chloro-6-methyl-benzo[b]thiophene-2-carboxylic acid (18), 70 ml of methanol and 10 ml of 1N NaOH is then added. The mixture is kept under reflux stirring in an inert atmosphere for 15 hours. 0.425 g of Pd/C (5% wet) is then added, and the reaction mixture is again maintained under reflux for 24 hours. The mixture is then cooled, diluted with methanol, filtered through a Celite bed, and the catalyst is washed with further methanol. The filtrate is then evaporated until dry at low pressure and the residue treated with 70 ml of 1N HCl and 250 ml of ethyl acetate. The organic phase is washed with brine (3×) and evaporated until dry, to obtain 1.82 g of compound (1) in the form of a white solid; HPLC purity=98.2%, yield=94.7%.

Provenance & Evidence