Decarboxylation-Driven Double Annulations: Innovative Multi-Component Reaction Pathways

A concerted five-component reaction strategy has been developed, featuring double [3+2] cycloadditions utilizing aspartic acid. This approach provides valuable insights into mechanistic pathways, allowing for the distinction between concerted and stepwise processes based on reaction efficiency and diastereoselectivity. Both aspartic and glutamic acids have been employed for a thorough evaluation and exploration of decarboxylation-driven double annulations. This method effectively constructs pyrrolizidine frameworks through a concerted double 1,3-dipolar cycloaddition with aspartic acid, as well as tetrahydropyrrolizinones via three-component double annulations, which include decarboxylative 1,3-dipolar cycloaddition and lactamization with glutamic acid. These highly convergent, decarboxylation-driven multicomponent reactions (MCRs) efficiently produce fused polyheterocyclic systems while being environmentally friendly, generating only CO₂ and water as byproducts.