Synthesis of propargylamine: pioneering a green path with non-conventional KA² coupling approach

The KA² coupling reaction is a well-explored and versatile method for forming C–C bonds in synthetic chemistry. It is composed of ketone, amine, and alkyne, which play a major role in the synthesis of propargylamines, known for their diverse biological activities and are used in treating neurogenetical disorders. The KA² coupling is highly challenging due to the low reactivity of ketimines toward nucleophilic attacks with metal acetylide intermediates formed by activating the C–H bond of the alkyne. Despite predominant studies conducted on thermal conditions for KA² coupling reactions, green and sustainable approaches like non-conventional methods still have a lot to achieve. This review article provides a comprehensive introduction to the non-conventional approach in the KA² coupling reaction, outlining its mechanisms and exploring future aspects.