TOTAL SYNTHESIS OF 3-O--L-SERINE AND A STEREOISOMER

Article abstract of DOI:10.1016/S0008-6215(00)90853-X

O-(5-Acetamido-3,5-dideoxy-D-glycero-α-D-galacto-2-nonulopyranosylonic acid)-(2->6)-O-(2-acetamido-2-deoxy-α-D-galactopyranosyl)-(1->3)-L-serine, a structural unit occuring in various submaxillary mucins, was sythesized for the first time by using O--(2->6)-3,4-di-O-acetyl-2-azido-2-deoxy-D-galactopyranosyl trichloroacetimidate (13) and N-(benzyloxycarbonyl)-L-serine benzyl ester as the key intermediates.The trichloroacetimidate 13 was prepared by starting from two monosaccharide synthons, namely, allyl 2-azido-2-deoxy-β-D-galactopyranoside and methyl (5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-β-D-galacto-2-nonulopyranosyl chloride)onate, which were coupled in the presence of silver triflate in tetrahydrofuran to give the desired α-(2->6)-linked disaccharide in moderate selectivity.