Silver-Catalyzed Diastereoselective Synthesis of Spirocyclic Pyrrolidine-Lactones by 1,3-Dipolar Cycloaddition

Abstract

The preparation of two enantiomerically enriched amino lactones as chiral starting substrates for asymmetric 1,3-dipolar cycloadditions is described. They act as precursors of the chiral imino lactones, which form in situ the corresponding azomethine ylides. They react with electrophilic alkenes under silver catalysis to afford spirolactone-pyrrolidines products. The sequential method consisting in one-pot imine formation → cycloaddition is optimized and compared with the multicomponent process. The scope of the reaction is studied as well as the stereochemical outcomes and the mechanistic details using DFT calculations and X-ray diffraction analysis.