Enantioselective Addition of Boronates to Chromene Acetals Catalyzed by a Chiral Brønsted Acid/Lewis Acid System
作者:Philip N. Moquist、Tomohiro Kodama、Scott E. Schaus
DOI:10.1002/anie.201003469
日期:2010.9.17
Chiral α,β‐dihydroxy carboxylic acids catalyze the enantioselective addition of alkenyl and aryl boronates to chromene acetals. The optimal carboxylic acid is the easily available tartaric acid amide shown in the scheme. Spectroscopic and kinetic mechanistic studies demonstrate that an exchange process generates a reactive dioxoborolane intermediate leading to enantioselective addition to the pyrylium
手性 α,β-二羟基羧酸催化烯基和芳基硼酸酯与色烯缩醛的对映选择性加成。最佳的羧酸是方案中所示的容易获得的酒石酸酰胺。光谱和动力学机理研究表明,交换过程产生反应性二氧硼杂环戊烷中间体,导致对映选择性加成到由色烯缩醛形成的吡喃鎓离子上。