Stereoselective Addition of Grignard-Derived Organocopper Reagents to N-Acyliminium Ions: Synthesis of Enantiopure 5- and 4,5-Substituted Prolinates

Article abstract of DOI:10.1021/jo00121a020

Alkylation of nonracemic N-acyliminium ions derived from proline and 4-substituted prolines has been extended to different types of Grignard-derived organocopper reagents.The reaction proceeds with high yield and stereoselectivity to yield 5-mono- and 4,5-disubstituted prolinates.The stereochemistry is controlled by the formation of a RCu-? complex intermediate between the N-acyliminium ion, the carbonyl group of the ester, and the copper species.