RADICAL REARRANGEMENT OF 2-O-(DIPHENYLPHOSPHORYL)GLYCOSYL BROMIDES - A NEW SYNTHESIS FOR 2-DEOXY DISACCHARIDES AND 2-DEOXY RIBONUCLEOSIDES

2-Deoxy-1-O-diphenylphosphoryl glycosides react with nucleophiles under mild conditions giving access to 2-deoxy disaccharides and nucleosides. The intermediate 2-deoxy-1-O-diphenylphosphoryl compounds were generated in situ by a radical 2 --> 1 migration of the phosphate ester group. This is the first observation of a rearrangement of a phosphate ester in radicals. ESR experiments and quenching of the radical at C2 by tin hydride or tin deuteride were used to detect the intermediates and to prove their structure.