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The trisaccharide segment of the phenolic glycolipid I of Mycobacterium leprae was synthesized effectively in the form of p-(2-methoxycarbonylethyl)phenyl glycoside by the condensation of p-(2-methoxycarbonylethyl)phenyl 4-O-benzyl-3-O-methyl-α-L-rhamnopyranoside and 2, 3-di-O-methyl-4-O-(2, 4-di-O-acetyl-3, 6-di-O-methyl-β-D-glucopyranosyl)-α-L-rhamnopyranosyl chloride in the presence of silver triflate and 1, 1, 3, 3-tetra-N-methylurea, and subsequent selective deprotection. This was then coupled to BSA by the acyl azide method, giving NT-P-BSA. The NT-P-BSA showed very high reactivity and specificity to leprosy sera. The trisaccharide-BSA conjugate with a β-linked rhamnosylrhamnose unit (βT-P-BSA) was also synthesized.

The disaccharide, 2,3-di-O-methyl-4-O-(3,6-di-O-methyl-β-d-glucopyranosyl)-l-rhamno-pyranose, the distal segment of phenolic glycolipid I, that is a specific antigen from Mycobacterium leprae, and some related disaccharides were synthesised as the glycosides of methyl 3-(p-hydroxyphenyl)propionate. The methyl 3-(p-hydroxyphenyl)propionate was coupled with 2,3,4-tri-O-acetyl-l-rhamnosyl bromide, deacetylated, acetonated, coupled with 2,4,6-tri-O-acetyl-3-O-methyl-d-glucosyl bromide, and converted into a variety of p-(2-methoxycarbonylethyl)phenyl 4-O-(3,6-di-O-methyl-d-glucopyranosyl)-containing disaccharides that are amenable to ready conjugation with protein carriers, thereby providing neo-glycoconjugates for the specific serodiagnosis of leprosy.