Synthesis of N-acetylglucosaminides of unconjugated and conjugated bile acids

Abstract

3-N- Acetylglucosaminides of unconjugated, glycine- and taurine-conjugated bile acids have been synthesized. Bile acids appropriately protected were condensed with acetochloroglucosamine through the 3α-hydroxyl group by means of the Koenigs-Knorr reaction using cadmium carbonate as a catalyst. Subsequent borohydride reduction and/or alkaline hydrolysis provided desired 3-N- acetylglucosaminides of unconjugated bile acids. Glycine-conjugates were obtained from N- acetylglucosaminides of unconjugated bile acids and ethyl glycinate by the carbodiimide method. The preparation of N- acetylglucosaminides of taurine-conjugates was attained by the Koenigs-Knorr reaction of bile acid p- nitrophenyl esters followed by condensation with taurine. 7-N- Acetylglucosaminides of ursodeoxycholates were prepared in a similar fashion. The convenient synthesis of 3-N- acetylglucosaminides of unconjugated bile acids is also described.