Dynamic stereochemistry of imines and derivatives. Part 13. The stereochemistry of the products from peroxyacid oxidation of bis-N-alkylaldimines

Abstract

Bis-N-alkylimines derived from glyoxal (1) and (2) and terephthalaldehyde (3) and (4) have been oxidised with m-chloroperoxybenzoic acid to give stereoisomeric mixtures of bis-oxaziridines. The bis-oxaziridines obtained from (1) have been separated and unequivocally assigned trans,trans[racemic](5a) and trans,trans[meso](5b) configurations by a combination of n.m.r. methods and asymmetric synthesis. Bis-oxaziridine products resulting from oxidation of the bis-imines (3) and (4) are also configurationally stable at nitrogen, and are formed as diastereoisomeric mixtures. Analysis of the bis-oxaziridine product mixture by ¹H and ¹³C n.m.r. indicates that the major components have the trans,trans and cis,trans stereochemistry though traces of the cis,cis isomer are probably present. Each of these components may be a mixture of meso and racemic isomers which are unresolved in the n.m.r. spectra. ¹H and ¹³C shifts and some ¹³C–H coupling constants are reported for the bis-oxaziridnes.