Oxidation of anomeric selenides, obtained from the radical azido phenylselenenylation of glycals, generates in situ extremely reactive glycosyl donors. When a 2-azido-2-deoxy-1-phenylselenomannoside is treated at a low temperature with perfluoro-cis-2,3-dialkyloxaziridine in the presence of a glycosyl acceptor, a (1-6)-β-linked mannopyranoside is obtained free from its α-isomer. 2-Phenyl-4,5-(3,4,6,-tri-O-methyl-1,2-di-deoxy-β-D-mannopyrano)-[2,1-d]-2-o xazoline, is isolated when 2-benzamido-2-deoxy-1-phenylselenomannoside is allowed to react with m-CPBA in dichloromethane
