AN NMR AND CONFORMATIONAL-ANALYSIS OF THE TERMINAL TRISACCHARIDE FROM THE SEROLOGICALLY ACTIVE GLYCOLIPID OF MYCOBACTERIUM-LEPRAE IN DIFFERENT SOLVENTS

The 1H- and 13C-n.m.r. spectra of allyl 2-O-[4-O-(3,6-di-O-methyl-β-d-glucopyranosyl)-2,3-di-O-methyl-a-l-rhamnopyranosyl]-3-O-methyl-a-l- rhamnopyranoside (3), a glycoside of the terminal trisaccharide found in the phenolic glycolipid I from Mycobacterium leprae, and those of the two component disaccharides, allyl 4-O-(3,6-di-O-methyl-β-d-glucopyranosyl)-2,3-di-O-methyl-a-l-rhamnopyranoside (1) and allyl 2-O-(2,3-di-O-methyl-a-l-rhamnopyranosyl)-3-O-methyl-a-l-rhamnopyranoside (2) have been assigned completely by 1D and 2D techniques. The preferred conformations, determined by chemical shift and n.O.e. studies, were different in D2O, CD3OD, and CDCl3. The preferred conformation of 3 accorded with the results of hard-sphere exo-anomeric (HSEA) calculations. © 1990.