Substrate-Controlled Direct α-Stereoselective Synthesis of Deoxyglycosides from Glycals Using B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub> as Catalyst
作者:Abhijit Sau、Carlos Palo-Nieto、M. Carmen Galan
DOI:10.1021/acs.joc.8b02613
日期:2019.3.1
α-stereoselective synthesis of deoxyglycosides from glycals. 2,3-Unsaturated α- O-glycoside products are obtained with deactivated glycals at 75 °C in the presence of the catalyst, while 2-deoxyglycosides are formed using activated glycals that bear no leaving group at C-3 at lower temperatures. The reaction proceeds in good to excellent yields via concomitant borane activation of glycal donor and nucleophile
B(C6F5)3使无金属的空前的基质控制的从糖类中脱氧糖苷的直接α-立体选择性合成成为可能。在催化剂存在下,在75°C下用失活的糖类获得2,3-不饱和α-O-糖苷产物,而使用在较低温度下C-3上不带有离去基团的活化的糖类形成2-脱氧糖苷。通过硼供体的糖基供体和亲核体受体的活化,该反应以良好的收率很好地进行。该方法以一系列稀有和生物学上相关的糖苷类似物的合成为例。