Synthesis of a Fusion-Isomeric Cellobionoimidazole and Its Evaluation against thesyn-Protonating Glycosidase Cel7A
作者:Narinder Mohal、Bruno Bernet、Andrea Vasella
DOI:10.1002/hlca.200590260
日期:2005.12
The fusion-isomeric cellobinoimidazole 2, a potential inhibitor of the syn-protonating β-glycosidase Cel7A, was synthesised by Koenigs–Knorr glycosylation of the α-D-arabinopyranoside 32, followed by selective hydrolysis. Glycosylation of 32 with acetobromoglucose 6 proceeded with poor diastereoselectivity, giving the desired 1,3-linked β-d-disaccharide 35 as minor product, besides the major 1,3-linked
通过对α-D-阿拉伯吡喃糖苷32进行Koenigs-Knorr糖基化,然后进行选择性水解,合成了融合异构体cellobinoimidazole 2(一种潜在的顺质子化β-糖苷酶Cel7A抑制剂)。用乙酰溴葡萄糖6进行32的糖基化,其非对映选择性差,除了主要的1,3-连接的α-d-二糖36以外,还提供了所需的1,3-连接的β -d-二糖35作为次要产物。Hg 2 + -促进的32的糖基化主要导致1,2-原酸酯33。顺序除去35个甲硅烷基,乙酰基和烯丙基会导致形成45:55的平衡混合物2和甘露聚糖配置的异构体39。同样,对36进行脱保护得到丙二咪唑42和甘露聚糖构型的异构体43的混合物。根据一个已知的协议,糖基受体32是由11个步骤合成的,D- lyxose的总收率为8–13%。α-d葡糖苷的甲硅烷基化阿拉伯糖部分13 - 19,33,34,和36采用4 Ç 1β -d-葡萄糖苷17和35的阿拉伯吡喃糖基部分以4