The isolation of the α-bromobenziminium hexafluoroantimonate 6, the first intermediate in the amide degradation with carbonyl bromide, was previously announced. Present studies reveal that using either COBr2 or PBr5, the very first intermediate is the iminium tribromide (7). Reaction of the crystalline tribromide with cyclohexane gave the monobromide 8 nearly quantitatively and in crystalline form. Heating of the cyclic iminium monobromide 8 to 120° ...
