Acetic Anhydride → 1h-Imidazo[1,2-b]pyrazole-1-carbaldehyde

Participants

Reaction Steps

A mixture of acetic anhydride (3.68 ml) and formic acid (3 ml) was stirred at room temperature for 1 hour. The solution was cooled in an ice-bath and 1H-imidazo-[1,2-b]pyrazole (2.1 g) was added thereto. The mixture was stirred at room temperature for 1 hour. The reaction mixture was evaporated and the residue was subjected to column chromatography on silica gel using a mixture of n-hexane and ethyl acetate (1:1) as an eluent. Fractions containing the object compound were combined and the solvent was evaporated to give 1-formyl-1H-imidazo[1,2-b]pyrazole (1.83 g). NMR (DMSO-d6, δ) : 6.20 and 6.28 (total 1H, each d, J=2Hz), 7.65-7.72 (1H, m), 7.71 (1H, d, J=2Hz), 7.87-7.92 (1H, m), 9.02 (1H, br s)

Provenance & Evidence