SELECTIVE REACTIONS OF THE FREE HYDROXYL-GROUPS OF 2,3,4,3',4'-PENTA-O-BENZYLSUCROSE

Selective transformations of the free hydroxyl groups in 2,3,4,3',4'-p enta-O-benzylsucrose (1) were studied. Oxidation of 1 with the Swern r eagent followed by reaction with Ph(3)P=CH-COOMe gave l-1',6,6'-tris-( E)(C-carbomethoxymethylene)sucrose (2) in ca.40% as the single product . Reaction of 1 with p-nitrobenzoic acid under Mitsunobu conditions ga ve O-p-nitrobenzoyl-2,3,4,3',4'-penta-O-benzylsucrose (3) which was ea sily converted into 2,3,4,3',4'-penta-O-benzyl-1'-methoxymethylsucrose (5). Reaction of 1 with one equivalent of pivaloyl chloride gave mono protected 2,3,4,3',4'-penta-O-benzyl-6'-O-pivaloylsucrose (6) [30% wit h triethylamine or 45% yield in the presence of (Bu(3)Sn)(2)O] togethe r with a small amount of diprotected 3,4,3',4'-penta-O-benzyl-6,6'-di- O-pivaloylsucrose (7).