| Abstract: | ABSTRACT Reaction of sugar derived phosphonates [Sug-C(O)CH2P(O)(OMe)2] with sugar aldehydes (Sug'-CHO) provides the higher enones of the general formula Sug-C(O)CH=CH-Sug' with the trans configuration of the double bond. The phosphonate method is superior to the previously used phosphorane methodology [Sug-C(O)CH=PPh3 + Sug'-CHO] since sugar phosphonates can be prepared in much higher yields and are much more nucleophilic than corresponding phosphoranes. The sugar enones are reduced to appropriate allylic alcohols with zinc borohydride; the stereoselectivity of this process is >97:3 (with the D-glycero isomer predominating) when the carbonyl group is placed at the α-position to the sugar ring. CD spectroscopy was used for the determination of the configuration of higher sugar allylic alcohols. |
