PREPARATION OF METHYL 4,6-DI-O-ACETYL-3-C-NITRO-2-ENOPYRANOSIDE DERIVATIVES AND THEIR REDUCTION WITH SODIUM BORODEUTERIDE

The conformationally flexible title compounds were prepared and subjec ted to reduction with sodium borodeuteride. Deuteride ion attacks excl usively from the side opposite of the anomeric methoxyl group. However , the stereoselectivity of a similar reduction of the corresponding 4, 6-O-benzylidene-beta-D-threo-2-enopyranoside derivative, adopting the H-0(5) conformation, was exceptionally low, suggesting that reduction of the 4,6-diacetate having the beta-D-threo configuration did not occ ur from the stable H-0(5) conformation, but from an unstable (H-5(0)) one.