Solvent-Dependent Divergent Functions of Sc(OTf)<sub>3</sub> in Stereoselective Epoxide-Opening Spiroketalizations
作者:Indrajeet Sharma、Jacqueline M. Wurst、Derek S. Tan
DOI:10.1021/ol500853q
日期:2014.5.2
A stereocontrolled synthesis of benzannulated spiroketals has been developed using solvent-dependent Sc(OTf)3-mediated spirocyclizations of exo-glycal epoxides having alcohol side chains. In THF, the reaction proceeds via Lewis acid catalysis under kinetic control with inversion of configuration at the anomeric carbon. In contrast, in CH2Cl2, Brønsted acid catalysis under thermodynamic control leads
使用溶剂依赖性 Sc(OTf) 3介导的具有醇侧链的外糖环氧化物的螺环化,已经开发了苯并环化螺缩酮的立体控制合成。在 THF 中,反应通过路易斯酸催化在动力学控制下进行,异头碳发生构型反转。相反,在 CH 2 Cl 2 中,热力学控制下的布朗斯台德酸催化导致构型保留。该反应适应各种芳基取代基和环大小,并提供立体化学多样化的螺缩酮。