Asymmetric Mannich reaction enabled synthesis of alkaloids.

The catalytic asymmetric Mannich reaction is a multicomponent reaction which affords β-amino carbonyl compounds by utilizing an aldehyde, a primary or secondary amine/ammonia, and a ketone. β-amino carbonyl scaffolds are crucial intermediates for the synthesis of naturally occurring bioactive compounds and their derivatives. The synthesized natural compounds exhibit a broad spectrum of biological activities including anti-fungal, anti-cancer, anti-bacterial, anti-HIV, anti-oxidant, and anti-inflammatory activities. Considering the significance of asymmetric Mannich reaction to access diverse biologically active natural products, its applications to afford the synthesis of naturally occurring alkaloids have been summarized here. This review article showcases the key role of asymmetric Mannich reaction in the synthesis of pharmaceutically potent naturally occurring alkaloids, i.e., indole alkaloids, monoterpenoid-indole alkaloids, diterpenoid alkaloids, iso-quinoline alkaloids, polyketide alkaloids, and pyrrolizidine alkaloids, etc., reported since 2015.