DIRECT DERIVATIZATION OF GLYOXAL INTO CHIRAL TEMPLATES PROVIDING COMPLETE DISCRIMINATION BETWEEN THE ALDEHYDE GROUPS

Condensation between glyoxal thiophenol and N-substituted (R)-phenylglycinol led to morpholine derivatives. The totally stereoselective formation of heterocycle 6 gives access to a chiral masked form of glyoxal in which the symmetry features of the dialdehyde have disappeared. The cyclisation is consistent with Baldwin rules for ring closures when applied to different competing pathways. AMI conformational calculations were used in order to rationalize the stereochemical outcome of the reported transformation. © 1990.