Transition Metal-free α-C-H Functionalization of Tertiary Amines Catalysed/Promoted by Acids: A Brief Review

C-H Functionalization of alpha-carbon of tertiary amines has been of great importance for the past two decades as N-heterocycles can be synthesized by this approach and these heterocycles are highly useful as drugs or drug precursors in the pharmaceutical industry. In this review article, we have summarized only the alpha-C-H functionalization reactions of tertiary amines that are catalysed or promoted by acids. These C-H functionalization reactions are usually catalysed by transition metal salts, although metal-free catalysts are also used. However, several such reactions have been reported that are efficiently catalysed by acids. They are cost-effective, have a simple purification process, less sensitive to air/moisture, and are relatively environmentally benign. However, this area has not received enough focus due to the lack of review articles, which encouraged us to write this review.