SYNTHETIC STUDY OF LIPOTEICHOIC ACID OF GRAM-POSITIVE BACTERIA .2. SYNTHESIS OF THE PROPOSED FUNDAMENTAL STRUCTURE OF ENTEROCOCCUS-HIRAE LIPOTEICHOIC ACID

The proposed fundamental structure of Enterococcus hirae lipoteichoic acid (LTA) was synthesized in order to elucidate the chemical structure responsible for the cytokine-inducing activity described for the natural LTA fraction of this bacteria. Synthesis was accomplished by coupling of the glycolipid part with the poly(glycerol phosphate) (PGP) part by using a phosphoramidite method. The glycolipid part was constructed by coupling of the phosphatidic acid moiety with a kojibiosyl diacylglycerol which had been prepared by stepwise glycosidation with glycosyl fluorides. Alpha-Selective glucosidations were effected by virtue of the 2,2,2-trichloroethoxycarbonyl (Troc) group introduced at the 6-hydroxyl function. p-Nitrobenzyl (NPM) and p-pivaloylaminobenzyl (PAB) groups were successfully applied to temporary protection of hydroxyl functions.