SYNTHESIS OF THE TRANS AND CIS HIGHER SUGAR ALLYLIC ALCOHOLS - DIRECTPRECURSORS OF DODECOSES

Reaction of -isopropylidene-alpha-D-galacto-hept-6-ynopyranose (3) wit h zyl-1,2-O-isopropylidene-alpha-D-xylo-pentodiulose (4) afforded two diastereoisomeric propargylic alcohols: 5a (D-glycero, R) and 5b (L-gl ycero, S) in 70% yield and in the 33:67 ratio. Hydrogenation of 5a and 5b over Pd/BaSO4 gave cis-allylic alcohols 6a and 6b. Semireduction o f the triple bond in 3 with tri-n-butyltin hydride afforded trans-olef in 7 which reacted with 4 yielding two diastereoisomeric trans-allylic alcohols: 8a (D-glycero, R) and 8b (L-glycero, S) in a 74% yield and a 72:28 ratio.