Enantioselective Aminocatalytic [2 + 2] Cycloaddition through Visible Light Excitation
作者:Thomas Rigotti、Rubén Mas-Ballesté、José Alemán
DOI:10.1021/acscatal.0c01413
日期:2020.5.1
to obtain enantioenriched cyclobutanes through [2 + 2] photocycloaddition under visible light irradiation is presented. This metal-free process does not require the use of any external photocatalyst, as it is catalyzed by a simple diamine which, upon condensation with an enone substrate, forms an iminium ion intermediate that absorbs in the visible light region. The direct excitation of such an intermediate
提出了在可见光下通过[2 + 2]光环加成反应获得对映体富集的环丁烷的不对称氨基催化活化策略。这种无金属的方法不需要使用任何外部光催化剂,因为它是由简单的二胺催化的,该二胺与烯酮底物缩合后,形成在可见光区域吸收的亚胺离子中间体。这种中间体的直接激发导致电荷转移(CT)激发态,该态以良好的对映异构体和非对映异构体比率和高收率解锁立体控制的分子间光环加成反应。最后,进行了DFT计算和实验以支持电荷转移行为和机理建议。