SYNTHESIS OF DERIVATIVES OF C-19 AND C-21 DIALDOSES

C-12-monosaccharide derivative 2 (obtained from C-12-dialdose 1 in 49% overall yield) was used as the starring material for the preparation of C-19- and C-21-monosaccharide derivatives. Coupling of aldehyde 3 ( prepared from the parent alcohol 2) with the sugar derived phosphonate s 8, 9, and 10 afforded the C-21- (11 and 12 respectively) and C-19- ( 13) monosaccharide derivatives. Aldehyde 3 reacted with phosphorane 7 and 14 under high pressure (13 kbarr) to afford C-21- and C-19-trans h igher sugar enones II and 13. No reaction between aldehyde 3 and Witti g-type reagents (7 and 14) was observed under atmospheric pressure.