Formic Acid → N-Methyl-2-(1,3-thiazol-2-yl)-1H-indole-7-amine hydrochloride

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Reaction Conditions

Reaction Steps

Under ice-cooling, formic acid (6.0 mL) was added dropwise to acetic anhydride (12.5 mL). After dropwise addition, the reaction mixture was stirred at 60° C. for 2 hr. Tetrahydrofuran (10 mL) was added to the reaction mixture, and a solution of 2-(1,3-thiazol-2-yl)-1H-indole-7-amine (10 g) in tetrahydrofuran (10 mL) was added dropwise under ice-cooling. The reaction mixture was stirred for 30 min and concentrated. Tetrahydrofuran (10 mL) was added to the obtained residue, and borane-tetrahydrofuran complex (1.0 M tetrahydrofuran solution, 30 mL) was added. The reaction mixture was stirred with heating under reflux for 1 hr. The reaction mixture was cooled to room temperature, and methanol (5 mL) was added. The reaction mixture was stirred with heating under reflux for 1 hr, concentrated, and the obtained residue was subjected to silica gel column chromatography (ethyl acetate:hexane=1:1). To the obtained a yellow oil was added 4N hydrogen chloride-ethyl acetate solution (30 mL). The obtained yellow crystals were collected by filtration, and washed with diethyl ether and hexane to give the title compound (10 g, yield 70%) as yellow crystals. melting point 89° C.

Provenance & Evidence