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 enantioselectiveaddition 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 enantioselectiveaddition to the pyrylium
Brønsted Acid/Lewis Acid Cooperatively Catalyzed Addition of Diazoesters to 2<i>H</i>-Chromene Acetals
作者:Yi Luan、Yue Qi、Hongyi Gao、Qianqian Ma、Scott E. Schaus
DOI:10.1002/ejoc.201403043
日期:2014.11
A novel Brønsted acid/Lewisacid dual catalyst system has been developed to promote an efficient C-C bond formation between a range of oxocarbenium precursors derived from chromene acetals and ethyldiazoacetate. The reaction proceeds under mild conditions and is tolerant of common functionalized 2H-chromene and isochromene acetals. In addition, an asymmetric variant of diazoacetate addition towards
已开发出一种新型布朗斯台德酸/路易斯酸双催化剂体系,以促进一系列衍生自色烯缩醛和重氮乙酸乙酯的氧代碳鎓前体之间有效形成 CC 键。该反应在温和的条件下进行,并且可以耐受常见的官能化 2H-色烯和异色烯缩醛。此外,还描述了重氮乙酸酯加成到 2H-色烯缩醛的不对称变体。继续研究包括对形成重氮酯取代的 2H-色烯的不对称诱导的进一步优化。