Aza-Hofmann Rearrangement: A Mini Review

The Hofmann rearrangement is a well-known method for the conversion of a primary amide into a primary amine with one less carbon atom. Classically, a mixture of halogen and a strong base is used as a reagent to perform the Hofmann rearrangement. In most cases, classical Hofmann rearrangement gave relatively poor yield and create enormous amount of waste products. Many modified version of Hofmann rearrangement has been developed to overcome the limitations associated with traditional Hofmann reaction. An important variant of Hofmann rearrangement is the aza-Hofmann arrangement in which amidines are used a starting materials instead of amides. This modification leads to the conversion of amidines to carbodiimide which on reaction with different nucleophiles such as carboxylates and amine lead to the corresponding amide or guanidine, respectively. In this article, hypervalent iodine mediated aza-Hofmann rearrangement of amidines has been described.