Recent Advances in Diversity Oriented Synthesis through Isatin-based Multicomponent Reactions

Isatins are well-known carbonyl electrophiles which allow a vast number of reactions initiated by nucleophilic attack on the C3 carbonyl group when used as starting materials. The most notable feature of isatins is that they serve as donors of oxindole fragments and furnish spirocyclic products in most cases. Because of their high reactivity and easy availability, isatins have been broadly used as building blocks in the synthesis of structurally complex and diverse heterocyclic compounds in multicomponent reactions (MCRs). Recent advances in diversity oriented synthesis with isatin-based MCRs are discussed in this Focus Review and are classified into different sections based on the key transformation involved in the reactions, such as 1,3-dipolar cycloaddition, Knoevenagel reaction, ring-opening of isatins and so on.