Deoxy sugars hydrogenolysis

Application of hydrogenolysis of benzylidene acetals to 2-amino-2-deoxy sugar derivatives was found to be possible.217 The reductive cleavage of benzyl 4,6-0-benzylidene-2-(benzyloxycarbonyl)amino-2-deoxy-a-D-glucopyranoside (209) gave, in a yield of 50%, a mixture of the 4-O-benzyl (210) and the 6-O-benzyl (211) derivatives. If the re-gioselectivity of this reaction, although notably inferior, was in ac-... 

S. Jacobsen and C. Pedersen, Preparation of 2-deoxy-sugars by hydrogenolysis of benzoylated glycopyranosyl bromides, Acta Chem. Scand., 27 (1973) 3111-3117. 

The 3-deoxyhexoses were obtained crystalline after separation on a column of cellulose, a rather tedious operation recently separation of these sugars by fractional crystallization has been reported (41). From the major unsaturated ester 27, 3-deoxy-D-ribo- and -arabino-hexose were shown to have been produced respectively in the ratio 66 34, and from ester 28 in the ratio 24 76. Saturation of the enol grouping of the esters 27 and 28 gives, therefore, the 1,2-cis products preferentially. However, some hydrogenolysis of the anomeric acetate group accompanies simple saturation of the double bond and poses another separation problem. 

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