A catalytic enantioselective formal [2+2] cycloaddition between α‐halo acroleins and electronically diverse arylalkenes is described. In the presence of (S)‐oxazaborolidinium cation as the catalyst, densely functionalized cyclobutanes containing two vicinal tetrasubstituted stereocenters were produced in high yields and high diastereoselectivities with excellent enantioselectivities. Mechanistic studies revealed that the cis isomer could be transformed into the trans isomer via an enantiocontrolled process. A gram‐scale reaction of this catalytic method was used to demonstrate its synthetic potential.

中文翻译：

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α-卤代丙烯醛的催化对映选择性[2 + 2]环加成反应：含有两个四取代立体中心的环戊二烯的构建。

描述了α-卤代丙烯醛与电子形式的芳基烯烃之间的催化对映选择性形式[2 + 2]环加成反应。在（S）-恶唑硼烷鎓阳离子作为催化剂的存在下，以高收率和高非对映选择性以及优异的对映选择性生产了含有两个邻位四取代立体中心的致密官能化环丁烷。机理研究表明，顺式异构体可以通过对映体控制的过程转化为反式异构体。此催化方法的克级反应用于证明其合成潜力。