A new stereoselective route to branched-chain nitro and amino sugars: synthesis of both enantiomers of decilonitrose and avidinosamine

Short, efficient, and highly diastereoselective syntheses of the title carbohydrates (15, 21, and 22), components of new anthracycline antibiotics, on a gram scale from readily available keto sugar precursors 6 and 17 are described. The syntheses feature the smooth and clean addition of organocerium compounds to benzyloxyimino derivatives 7 and 18; which provide the branched-chain hydroxyamino sugars (9, 20) bearing an equatorial methyl group with complete regio- and stereocontrol. Treatment of oximino deoxy sugars (7, 18) with methyllithium resulted in β-elimination and afforded pyranoid 1-enol 3-one oximes (8, 19)