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The incorporation of radioactivity in vitro from UDP-[14C]glucose into endogenous acceptors in a crude enzymatic preparation from Acetobacter xylinurn is described.A fraction of the total incorporated radioactivity could be extracted with organic solvents, like butanol. The remainder was mostly solubilized by hot alkali, leaving an insoluble fraction.No incorporation was observed in the absence of magnesium ions. could only partially replace Mg2+, and had an inhibitory effect when both ions were present.Analysis of the butanol-soluble fraction permitted the isolation of a t least three components characterized as: lipid-diphosphate a-glucose, lipid-diphosphate a-cellobiose and lipid-monophosphate @-galactose.I n the presence of [,9-3-a2P]UDP-glucose the system incorporated radioactivity only into the diphosphate derivatives, indicating the transfer of a a-glucose I-phosphate group from UDPglucose. Experiments with doubly labelled substrate confirmed these results.The role these compounds might play in polysaccharide biosynthesis is discussed.The role of lipid-linked intermediates in the biosynthesis of bacterial polysaccharides seems to be well established in several systems [l].The synthesis of lipopolysaccharides [2,3], peptidoglycans [4], and capsular polysaccharides [5] includes a lipid-diphosphate sugar stage in which the lipid has been shown to be undecaprenol, a polyisoprenol made of a chain of eleven isoprene units in which the ty-residue carries an allylic alcohol. All these polysaccharides are quite complex and several different sugars, and even amino acids, constitute the basic or repeating unit of the polymer. The presence of an intermediate stage seemed quite suitable to allow the formation of this repeating unit prior to its polymerization into the final product .

A new simple 3‐step synthesis of 1‐O‐acetyl‐2,3,5‐tri‐O‐benzoyl‐β‐Dribofuranoside is described. D‐Ribose is methylated to 1‐O‐methylribofuranoside and the latter benzoylated to 1‐O‐methyl‐2,3,5‐tri‐O‐benzoyl‐D‐ribofuranoside. Acetolysis with a mixture of acetic acid, acetic anhydride and sulfuric acid furnishes directly and in good yield pure 1‐O‐acetyl‐2,3,5‐tri‐O‐benzoyl‐β‐D‐ribofuranoside.

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