Neighboring Group Participation in Glycosylation Reactions by 2,6-Disubstituted 2-<i>O</i>-Benzoyl groups: A Mechanistic Investigation
作者:Rohan J. Williams、Nathan W. McGill、Jonathan M. White、Spencer J. Williams
DOI:10.1080/07328303.2010.508141
日期:2010.7.1
Variable yields and glycosylation stereoselectivity were obtained for NIS/TfOH-medi- ated reaction of 4-methoxyphenyl 2,4,6-tetra-O-acetyl-β-D-galactopyranoside and thiogalactosides bearing acetyl, benzoyl, 2,6-dimethoxylbenzoyl, 2,4,6-trimethylbenzoyl, or 2,6-dichlorobenzoyl groups at the 2-positions and acetyl at the remainder. X-ray structures of 4-methylphenyl 2,3,4,6-tetra-O-(2,4,6-trimethylb
对于NIS / TfOH介导的4-甲氧基苯基2,4,6-四-O-乙酰基-β-D-吡喃半乳糖苷和带有乙酰基,苯甲酰基,2,6-二甲氧基苯甲酰基的硫代半乳糖苷的反应,获得了不同的收率和糖基化立体选择性。在2-位的是2,4,6-三甲基苯甲酰基或2,6-二氯苯甲酰基,其余为乙酰基。4-甲基苯基2,3,4,6-四的X射线结构Ö - (2,4,6-三甲基苯甲酰)-1-硫代β-d-galactopyr anoside和4-甲基苯基3,4- ø -异亚丙基-2,6-二-O-(2,4,6-三甲基苯甲酰基)-1-硫代-β-D-吡喃半乳糖苷显示轻微扭曲的4 C 1椅子构象。可变温度NMR显示4-甲基苯基2,3,4,6-tetra- O的活化-(2,4,6-三甲基苯甲酰基)-1-硫代-β-D-吡喃半乳糖苷仅提供二恶唑鎓离子,而4-甲基苯基3,4,6-三-O-乙酰基-2- O-(2,4, 6-三甲基苯甲酰基)-1-