Synthesis, and carbon-13 n.m.r. study, of O-α-l-rhamnopyranosyl-(1→3)-O-α-l-rhamnopyranosyl-(1→2)-l-rhamnopyranose and O-α-l-rhamnopyranosyl-(1→3)-O-α-l-rhamnopyranosyl (1→3)-l-rhamnopyranose, constituents of bacterial, cell-wall polysaccharides
作者:Vince Pozsgay、Pál Nánási、András Neszmélyi
DOI:10.1016/s0008-6215(00)85921-2
日期:1981.4
hydrogenolysis, With benzyl 2,3,4-tri- O -benzyl-β- d -galactopyranoside, compound 18 gave an ≈3:2 mixture of benzyl 2,3,4-tri- O -benzyl-6- O -[2,4-di- O -acetyl-3- O -(2,3,4-tri- O -acetyl-α- l -rhamnopyranosyl)-α- l -rhamnopyranosyl]-β- d -galactopyranoside and 4- O -acetyl-3- O -(2,3,4-tri- O -acetyl-α- l -rhamnopyranosyl)-β- l -rhamnopyranose 1,2-(1,2,3,4-tetra- O -benzyl-β- d -galactopyranose-6-yl (orthoacetate)
摘要通过苄基2,4-( 7)和3,4-二-O-苄基-α-1-鼠李糖吡喃糖苷(8)与2,3,4-三-O-乙酰基-α-1-鼠李糖吡喃糖基溴化物,然后脱保护。通过与8和7反应,得到19的过-乙酰基α-溴化物(18),得到标题三糖的保护衍生物(分别为25和23),通过Zemplen脱乙酰基化和催化得到25和23。氢解,用苄基2,3,4-三-O-苄基-β-d-吡喃半乳糖苷,化合物18得到≈2:3的苄基2,3,4-三-O-苄基-6-O-[混合物] 2,4-二-O-乙酰基-3-O-(2,3,4-三-O-乙酰基-α-1-鼠李糖基吡喃糖基)-α-1-l-鼠李糖基吡喃糖基]-β-d-吡喃半乳糖苷和4-O -乙酰-3-O-(2,3,游离α-1-rhamnopyranose在HO-2或-3处由α-1-rhamnopyranosylation诱导的α-碳原子下场位移为7.4-8.2 ppm,比(还原端)鼠李糖高约1