Selective bromoacetylation of alkyl hexopyranosides: A facile preparation of intermediates for the synthesis of (1→6)-linked oligosaccharides
作者:Thomas Ziegler、Pavol Kováč、Cornelis P.J. Glaudemans
DOI:10.1016/0008-6215(89)85018-9
日期:1989.12
(30) and methyl 3-O-benzyl-2,4-di-O-benzoyl-beta-D-galactopyranoside (15). These compounds can be used as nucleophiles for the synthesis of (1----6)-linked oligosaccharides. The conversion 1----5 could be performed without isolation of the intermediates. The treatment of bromoacetyl derivatives with benzoyl chloride in pyridine resulted in the benzoylation of the remaining free hydroxyl groups and the
甲基β-D-半乳糖-(1),α-D-半乳糖-(6),β-D-葡萄糖-(18),(22)和α-D-甘露糖吡喃糖苷(31)的溴乙酰化作用,以及苄基β-D-吡喃葡萄糖苷(27)以50-60%的收率得到相应的6-O-溴乙酰基衍生物2、7、19、23、32和28。3-O-苄基-β-D-吡喃半乳糖苷的甲基溴乙酰化(11)提供了甲基3-O-苄基-6-O-溴乙酰基-β-D-吡喃半乳糖苷(12,60%)以及3-O-甲基苄基-2,6-二-O-溴乙酰基-β-D-吡喃半乳糖苷(13,14%)。将化合物2、7、19、23、32、28和12进行苯甲酰化,将得到的完全保护的衍生物用硫脲脱卤乙酰化,得到β-半乳糖的甲基2,3,4-三-O-苯甲酰基-D-吡喃葡萄糖苷(5),α-半乳糖(9),β-葡萄糖(21),α-葡萄糖(25)和α-甘露糖(34)以及苄基2,3,4-三-O-苯甲酰基-β-D-吡喃葡萄糖苷(30)和甲基3-O-苄基-2