Tetrahydrofuran → 2-Ethyl-4-methoxybenzothiazole-7-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

A mixture of 7-bromo-2-ethyl-4-methoxybenzothiazole (2.96 g), palladium (II) acetate (240 mg), bis-diphenylphosphinopropane (900 mg), and triethylamine (15 ml) in tetrahydrofuran (150 ml) and water (20 ml) was charged with 150 psi of carbon monoxide and stirred at 90° C. for 3 days. The organic solvent was removed in vacuo and the residue partitioned between ethyl acetate (50 ml) and aqueous sodium hydroxide (1M, 2×50 ml). The aqueous extracts were combined, acidified to pH 4 with glacial acetic acid, extracted with ethyl acetate (3×50 ml). The organic extracts were combined, dried over magnesium sulphate (5 g), filtered, and the filtrate evaporated in vacuo Recrystallisation from ethyl acetate/hexane gave the desired product as an off-white solid (2.2 g). TLC Rf 0.30 (50%ethyl acetate in hexane)

Provenance & Evidence