Metal–Organic Frameworks Invert Molecular Reactivity: Lewis Acidic Phosphonium Zwitterions Catalyze the Aldol-Tishchenko Reaction
作者:Gerald Bauer、Daniele Ongari、Xiaoying Xu、Davide Tiana、Berend Smit、Marco Ranocchiari
DOI:10.1021/jacs.7b10928
日期:2017.12.20
commonly known nucleophile, is identified as the catalytic active species. This zwitterion favors nucleophilic character in solution, whereas once confined within the framework, it becomes an electrophile yielding Aldol-Tishchenko selectivity. Computational investigations reveal a structural change in the phosphonium moiety induced by the steric confinement of the framework that makes it accessible and an
本文描述了金属有机骨架 (MOF) 作为添加剂对正烷基醛在甲基乙烯基酮和三苯基膦存在下的反应的影响。在没有 MOF 的情况下,观察到预期的 Morita-Baylis-Hillman 产物,即 β-羟基烯酮。在具有 UMCM-1 和 MOF-5 拓扑结构的 MOF 存在下,该反应对 Aldol-Tishchenko 产物(2-烷基-1,3-二醇的 1 和 3 正烷基酯)具有选择性,这在有机催化中是前所未有的。(3-oxo-2-butenyl)triphenylphosphonium 两性离子,一种众所周知的亲核试剂,被确定为催化活性物质。这种两性离子有利于溶液中的亲核特性,而一旦被限制在框架内,它就会成为产生 Aldol-Tishchenko 选择性的亲电试剂。