A highly diastereoselective synthesis of 4-octulose and 2-deoxy-4-octulose from a D-fructose derivative

Bishydroxylation of methyl (Z)-2,3-dideoxy-4,5:6,7-di-O-isopropylidene-beta-D-arabino-oct-2-ene-4-ulo-4,8-pyranosonate 1 with osmium tetraoxide proceeded with extremed high diastereoselectivity to give only methyl 4,5:6,7-di-O-isopropylidene-beta-D-arabino-L-erythro-oct-4-ulo-4,8-pyranosonate 2. Configurations of the new stereogenic centers (C-2,3) in 2 were determined by degradation of the C-5,6,7,8 fragment to the well-known methyl 2,3,4-tri-O-methyl-D-(+)-erythronate. 7. Transformation of 2 into the required D-arabino-L-erythro-oct-4-ulosa 10, was achieved by a methodology that implied, protection to 8, reduction of the ester group in 8 to a hydroxymethyl group in 9, and finally deprotection to the free D-arabino-L-erythro-oct-4-ulosa 10. On the other hand, epoxidation reaction on (E)-2,3-dideoxy-4,5:6,7-di-O-isopropylidene-beta-D-arabino-oct-2-ene-4-ulo-4,8-pyranose 11 afforded only the corresponding 2,3-anhydro derivative 12 with beta-D-arabino-D-threo configuration, as could be demonstrated by degradation to (S)-1,2,4-trimetoxybutane 16, which synthesis is reported herein. Copyright (C) 1996 Elsevier Science Ltd.