Isoamyl Nitrite → 6-Benzothiazolecarboxylic acid, 4-methoxy-, methyl ester

Participants

Reaction Conditions

Reaction Steps

To a stirred solution of methyl 2-amino-4-methoxy-1,3-benzothiazole-6-carboxylate (100 g, 0.42 mol) in DMF (1 L) was added drop wise isoamyl nitrite (108 g, 0.92 mol) at 65° C. Then the resulting mixture was stirred at 65° C. for 20 min. TLC (EtOAc/Petroleum ether 1:4) showed the reaction was complete. After cooling to ambient temperature, the mixture was poured into ice water (1 L). The resulting mixture was extracted with EtOAc (1 L×3). The combined organic layers were washed with water (1 L×2), dried over Na2SO4 and concentrated in vacuum. The residue was purified by chromatography (silica gel, EtOAc/Petroleum ether 1:50 to 1:10) to afford the product (22 g, 23%) as a yellow solid. 1H NMR (400 MHz, CDCl3): δ 9.050 (s, 1H), 8.285-8.281 (d, 1H), 7.592-7.587 (d, 1H), 4.110 (s, 3H), 3.965 (s, 3H).

Provenance & Evidence