A NOVEL ROUTE TO DEOXYGENATED SUGARS FROM UNPROTECTED SUBSTRATES

An efficient synthesis of deoxy and dideoxy sugars was achieved in two consecutive steps. unprotected carbohydrates were selectively tioacylated at first by using 2-mercapto-5-methyl-1,3,4- thiadiazole aryloxythiocarbonyl derivatives. primary and/or secondary corresponding thionocarbonates were also obtained. these intermediates were then deoxygenated under mild conditions without protection of free hydroxyl groups by using diphenylsilane in the presence of trieehtyborane and oxygen. this process which offers several advantages seems to be compatible with natural products such as sugars and was then successfully applied to neopentyl hydroxyl group.