Asymmetric synthesis at nitrogen by oxidation of imines with m-chloroperbenioic acid in the presence of optically active carbinols. Absolute stereochemistry of chiral alcohol-imine-peracid solvates

Abstract

Optically active oxaziridines, stable at the asymmetric nitrogen atom, have been obtained by oxidation of imines with m-chloroperbenzoic acid in the presence of chiral carbinols. The optical purity of the reaction products increases on decreasing the temperature and depends on the starting imine and on the nature and relative amount of the chiral solvent. The absolute stereochemistry of the oxaziridines obtained is correlated with the chirality of the alcohol used. Specific carbinol–imine solvation models are discussed in the light of enantiomeric ¹H n.m.r. nonequivalence and asymmetric reaction results, obtained by using chiral trifluoromethylcarbinols, imine substrates, and oxaziridine products of well established configuration.