Pozsgay V, Robbins J B
Laboratory of Developmental and Molecular Immunity, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
Carbohydr Res. 1995 Nov 7;277(1):51-66. doi: 10.1016/0008-6215(95)00199-4.
Stereocontrolled, stepwise synthesis of decyl glycosides of alpha-(1-->2)-linked di- to pentaglucosides (1-5) is described; these constitute fragments of Polysaccharide II of Mycobacterium tuberculosis. Phenyl 3,4,6-tri-O-acetyl-2-O-benzyl-1-thio-alpha-D- glucopyranoside (7) was used as the single key intermediate, obtained from 1,3,4,6-tetra-O-acetyl-2-O-benzyl-beta-D-glucopyranose (6) and PhSSiMe3. Halogenolysis of 7 afforded the isolated beta bromide (10) and beta chloride (13). Solvolysis of 10 with decanol without heavy metal salts gave decyl 3,4,6-tri-O-acetyl-2-O-benzyl-alpha-D-glucopyranoside (14) in a highly stereoselective reaction, in high yield. Subsequent, iterative hydrogenolytic removal of the O-benzyl group and glycosylation with the beta-chloride 13 under catalysis by silver salts afforded the protected di- to penta-saccharide glycosides 16, 19, 21, and 23, which were conventionally deblocked.
描述了α-(1→2)连接的二糖至五糖糖苷（1-5）的癸基糖苷的立体控制逐步合成；这些构成了结核分枝杆菌多糖II的片段。苯基3,4,6-三-O-乙酰基-2-O-苄基-1-硫代-α-D-吡喃葡萄糖苷（7）用作单一关键中间体，由1,3,4,6-四-O-乙酰基-2-O-苄基-β-D-吡喃葡萄糖（6）和PhSSiMe3制得。7的卤解得到分离的β-溴化物（10）和β-氯化物（13）。10与癸醇在无重金属盐的情况下进行溶剂解反应，以高立体选择性反应高产率得到3,4,6-三-O-乙酰基-2-O-苄基-α-D-吡喃葡萄糖苷癸酯（14）。随后，通过催化氢解依次除去O-苄基，并与β-氯化物1-3在银盐催化下进行糖基化反应，得到受保护的二糖至五糖糖苷16、19、21和23，然后按常规方法脱保护。
