Anomalous halogenation of N-(2-acetylbenzofuran-3-yl)acetamide

Abstract

N-(2-Acetylbenzofuran-3-yl)acetamide (6) reacts with sulphuryl chloride or chlorine to give N-(2-chlorobenzofuran-3-yl)acetamide (9) in high yield. Experiments with radical inhibitors suggest the reaction with sulphuryl chloride to be electrophilic in nature. In contrast, the acetamide (6) reacts with bromine or phenyltrimethyl-ammonium tribromide (PTAT) to give a high yield of the bromoacetyl derivative (2). 3-Methylbenzofuran-2-yl methyl ketone (8) reacts with sulphuryl chloride or PTAT to give the corresponding halogenoacetyl derivative (3) or (4).