Application of sugar phosphonates for the preparation of higher carbon monosaccharides

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 phosph onate method is superior to the previously used phosphorane methodology [Su g-C(O)CH=PPh3 + Sug'-CHO] since sugar phosphonates can be prepared in much higher yields and are much more nucleophilic than corresponding phosphorane s. The sugar enones are reduced to appropriate allylic alcohols with inc bo rohydride; the stereoselectivity of this process is >97:3 (with the D-glyce ro isomer predominating) when the carbonyl group is placed at the a-positio n to the sugar ring. CD spectroscopy was used for the determination of the configuration of higher sugar allylic alcohols.