Stereoretentive Catalytic [3+2]/[3+3]-Cycloaddition of Nonracemic Donor-Acceptor Cyclopropanes: Synthesis of Substituted Pyrrolidines and 1,2-Oxazinanes

A highly enantioselective preparation of substituted pyrrolidines and 1,2-oxazinanes has been achieved via stereoretentive [3 + 2]/[3 + 3]-cycloaddition of nonracemic donor-acceptor cyclopropanes with imines, triazines, and nitrones in good to high yields with broad scope under mild reaction conditions. In comparison with the well-documented approach to donor- acceptor cyclopropane reactions using racemic cyclopropane reactants and a catalyst with chiral ligands, this report features applications of enantioenriched donor-acceptor cyclopropanes as cycloadduct reactants with achiral catalysts.

Automated summary

This study achieved a highly enantioselective synthesis of substituted pyrrolidines and 1,2-oxazinanes via stereoretentive [3 + 2]/[3 + 3]-cycloaddition of nonracemic donor-acceptor cyclopropanes with imines, triazines, and nitrones. The reactions were conducted under mild conditions and showed good to high yields with broad applicability. Compared to previous approaches using racemic cyclopropane reactants and chiral ligand catalysts, this study utilized enantioenriched donor-acceptor cyclopropanes as reactants with achiral catalysts.