A general approach to the synthesis of dideoxy and trideoxyiminoalditols from beta-D-glycosides

Imino sugars (also called azasugars), a class of compounds of which the 1,5-dideoxy and 1,5,6-trideoxyiminoalditols are members, are important glycosidase inhibitors with very high potential as drugs. Their potential therapeutic applications range from the treatment of diabetes to cancer and AIDS. We present here a general method for the preparation of such compounds with the D-gluco and D-galacto configurations starting from beta-D-glycosides. The procedure is especially appealing because of its high stereoselectivity and straightforwardness. The key steps are the selective oxidation of the glycosides to hexulosonic acids and reduction of the oxime derivatives to lactams, which are further reduced to the target compounds. The C-6 position can be deoxygenated during the reduction if it bears an acetoxy group. Trideoxy imino sugars are then produced. Deacetylation prior to oxime reduction gives dideoxy compounds.