Glycosylation with 2-Acetamido-2-deoxyglycosyl Donors at a Low Temperature: Scope of the Non-Oxazoline Method
作者:Ryoichi Arihara、Kosuke Kakita、Noritoshi Suzuki、Seiichi Nakamura、Shunichi Hashimoto
DOI:10.1021/acs.joc.5b00138
日期:2015.5.1
glycosyl diethyl phosphites and 4,6-O-benzylidene-protected galactosyl diethyl phosphite each reacted with a variety of acceptor alcohols in the presence of a stoichiometric amount of Tf2NH in CH2Cl2 at −78 °C to afford the corresponding β-glycosides in good to high yields with complete stereoselectivity. Some experiments provided strong evidence that the corresponding oxazolinium ions are not responsible
研究了1,2-反式-β-连接的2-乙酰氨基-2-脱氧糖苷的直接构建。3,4,6-三-O-苄基和3,4,6-三-O-乙酰基保护的糖基二乙基亚磷酸酯和4,6 - O-亚苄基保护的半乳糖基亚磷酸二乙酯分别与多种受体反应化学计算量的Tf 2 NH在CH 2 Cl 2中存在的醇在-78°C的条件下,以完全高的立体选择性提供高至高收率的相应β-糖苷。一些实验提供了有力的证据,表明相应的恶唑啉鎓离子不负责该反应。我们证明了与相应的亚糖基亚氨酸酯和硫代糖苷的糖基化作用也在低温下进行,表明这些供体是亚磷酸酯的有吸引力的替代物的可能性。基于用2-乙酰氨基-2-脱氧甘露糖基供体获得的结果,提出了一种合理的反应机理,该机理以糖基三氟酰亚胺和接触离子对为反应性中间体。