Viewing the Ritter reaction through single electron transfer lenses

Abstract

Ritter reaction presents itself as the modern workhorse of amination reactions. What started as the amidation of tertiary carbon centres has spread to alkenes, carboxylic acids, as well as alkanes. The last decade has seen a tremendous increase in the utilization of Single Electron Transfer (SET) techniques in organic synthesis. Ritter amination has evolved along these lines as well, providing an unparalleled platform for incorporating amines into substrates of various types. In addition to photoredox and electrocatalytic niches, such SET-mediated reactions have been elegantly achieved using conventional oxidants, organocatalysts and transition metal-based complexes. In this review we present an in-depth discussion about the various reports on SET-based Ritter aminations, placing emphasis on the transition metal-mediated, organocatalytic, and conventional oxidant-based procedures in addition to the photoredox ones. The review is divided into two categories namely Ritter amination of alkenes and Ritter amination of sp³-C centres which are further sub-categorized appropriately with respect to the types of reactions.