2-Deoxy sugars from glycals

S. Sabesan and S. Neira, Synthesis of 2-deoxy sugars from glycals, J. Org. Chem., 56 (1991) 5468-5472. 

The azidonitration route to 2-amino-2-deoxy sugars from D-glycal should be compared with the alternative route exploiting the addition of nitrosyl chloride (Section 7.2.1.1). Both methods have been tested on the synthesis of intermediates of D-lactosamine, and the azidonitration method was considered more efficient95. 

Glycals are also available from 2-deoxy sugars by acid- or base-induced eliminations ofanomeric substituents. These methods are limited by the availability ofthe 2-deoxy sugars, for which the glycals themselves are the most obvious synthetic precursors. However, examples of these methods (Scheme 5.43) are in the direct preparation oftri-O-benzyl-D-glucal (14) from 2-deoxy-tri-O-benzyl-D-glucopyranose (13) via its 1-O-mesylate [117], and di-O-benzyl-D-ribal (16) from the phenylselenide 15 via oxidation to the selenoxide followed by elimination [118]. 

Synthesis from carbohydrate derived 2-deoxy lactones. Routes to C-l glycals from 2-deoxy sugar pyranolactones have been described. The general strategy is outlined in Scheme 9. 

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