CAPSULAR POLYSACCHARIDE OF STREPTOCOCCUS-PNEUMONIAE TYPE 19F - SYNTHESIS OF THE REPEATING UNIT

A new and more versatile synthesis of beta-D-ManpNAc-(1 --> 4)-alpha-D -Glcp-(l --> 2)-alpha-L-Rhap, the trisaccharide repeating unit of the Streptococcus pneumoniae type 19F capsular polysaccharide, is describe d. The present approach allows a simple access to different fragments containing the trisaccharide and the conjugation of the product(s) to a protein through the selective manipulation of the anomeric position at the reducing end and of the HO-4 function at the nonreducing end. T he synthetic scheme shows an efficient application of the sulfoxide me thod for the stereoselective and high yielding formation of the glycos idic linkages. (C) 1998 Elsevier Science Ltd. All rights reserved.