Oxidation of amine α-carbon to amide: a review on direct methods to access the amide functionality
A number of methods have been adopted for the synthesis of amides; among these methods, the oxidation of an amine to an amide is growing in interest as a means to prepare this imperative functional group. Amines possessing α-CH, α-CH2, and α-CH3 groups have been utilized in the oxidation reactions to give the corresponding amides. The amides in turn have been used in oxidation reactions to prepare imides. This review covers the literature relating to the construction of amide bonds from amines using transition metal-based oxidants and non-metal-based oxidants, and also the key area of the use of molecular oxygen as an oxidant in the presence of catalysts. The use of molecular oxygen in the metal-/non-metal-catalysed oxidation of amines has led to the development of a powerful methodology for amide bond formation.