A Thermodynamic Preference of Chiral <i>N</i>-Methanesulfonyl and <i>N</i>-Arenesulfonyl 2,3-<i>cis</i>-3-Alkyl-2-Vinylaziridines over Their 2,3-<i>Trans</i>-Isomers:  Useful Palladium(0)-Catalyzed Equilibration Reactions for the Synthesis of (<i>E</i>)-Alkene Dipeptide Isosteres

Abstract

Palladium(0)-catalyzed reactions of N -methanesulfonyl- or N -(arenesulfonyl)-3-alkyl-2-vinylaziridines reveal that 2,3- cis -isomers are more stable than the corresponding 2,3- trans -isomers in accord with ab initio calculations. A highly stereoselective synthetic route to ( E )-alkene dipeptide isosteres having desired stereochemistries from 2,3- cis -3-isobutyl-2-vinylaziridine by the use of organocopper chemistry is also presented.