vonBraun Cyanogen Bromide Reaction

Abstract

The dealkylation of tertiary amines by means of the treatment with cyanogen bromide to give disubstituted cyanamides and alkyl bromides is generally referred to as the von Braun cyanogen bromide reaction, or von Braun reaction. For cyclic amines, both cyclic cyanamides and ω‐bromoalkyl cyanamides might form, depending on the reactivity of the individual alkyl groups. In addition, if the aryl component is activated by an electron‐donating group, the reaction may lead to the bromination or cyanation of the aromatic nucleus. It has been reported that the von Braun reaction can be accelerated by the addition of a Lewis acid. This reaction has been applied for the degradation of alkaloids for the purpose of early structural elucidation as well as the preparation of alkaloid derivatives.