Recent applications of vinylethylene carbonates in Pd-catalyzed allylic substitution and annulation reactions: Synthesis of multifunctional allylic and cyclic structural motifs

Vinylethylene carbonates (VECs) are diverse and functionalized structural frameworks that can undergo transitional metal-catalyzed decarboxylative process to generate π-allyl-Pd intermediate, which in turn can react with a broad range of carbon and hetero nucleophiles to afford highly stereoselective construction of C–C and C–Het (N, O, S) bonds. The advent of VECs as substrates for transition metal catalyzed highly regio-, stereo-, and enantioselective allylic substitutions and annulation reactions has spurred widespread interest from the research community in recent years. As a result, these synthetic methods allow direct access to versatile building blocks, important in modern synthetic and medicinal chemistry. To the best of our knowledge, Pd-catalyzed allylic substitution of VECs with carbon and hetero nucleophiles (N, O and S) has not been reviewed yet. This review provides the first updated account on the recent advances and application of VECs in palladium catalyzed allylic substitution since 2013. Moreover, owing to the growing interest in deployment of zwitterionic π-allyl Pd-intermediates in annulation reactions to access diverse heterocyclic structural motifs, recent literatures on the decarboxylative annulation modes of VECs have also been reviewed and discussed.