Synthetic applications of biologically important Mannich bases: An updated review

Mannich bases are the beta-amino ketones carrying compounds. Mannich reaction is a nucleophilic addition reaction (nucleophiles such as halogen ions (I-, Br-, Cl- ), the hydroxide ion (OH- ), cyanide ion (CN-), ammonia and water, which involves the condensation of three components, viz., ammonia or a primary amine or a secondary amine or with amides, a non-enolizable aldehyde, usually formaldehyde and a compound containing an active hydrogen atom. These three compounds condense with the concomitant release of the water molecule to produce a new base known as a mannich base, in which the active hydrogen is replaced by an amino methyl group. During the past decades, there has been a great deal of interest in the synthesis of mannich bases. Mannich base can be synthesized by using microwave irradiation, one pot, catalyst-free, retrospective asymmetric synthesis, solvent-free and ultrasonic-assisted synthetic techniques. The literature studies enlighten the fact that mannich bases are a key step in the synthesis of a wide variety of natural products, pharmaceuticals and so forth. Mannich bases play a vital role in the coordination chemistry and the development of metal complexes. Mannich bases have remained an important and popular area of research due to their simple synthesis, adaptability and diverse range of applications. Thus, mannich bases and their derivatives may be further used for enormous biological applications with potent effects.