Cyclic Ureate Tantalum Catalyst for Preferential Hydroaminoalkylation with Aliphatic Amines: Mechanistic Insights into Substrate Controlled Reactivity
作者:Pargol Daneshmand、Sorin-Claudiu Roşca、Rosalie Dalhoff、Kejun Yin、Rebecca C. DiPucchio、Ryan A. Ivanovich、Dilan E. Polat、André M. Beauchemin、Laurel L. Schafer
DOI:10.1021/jacs.0c04579
日期:2020.9.16
accessible, N,O-chelated cyclic ureate tantalum catalyst was prepared and characterized by X-ray crystallography. This opti-mized catalyst can be used for the hydroaminoalkylation of 1-octene with a variety of aryl and alkyl amines, but notably enhanced catalytic activity can be realized with challenging N-alkyl secondary amine substrates. This catalyst offers turnover frequencies of up to 60 h-1, affording
未活化的烯烃与简单的仲烷基胺的有效和催化胺化优先实现。制备了空间可接近的 N,O 螯合环脲酸钽催化剂,并通过 X 射线晶体学表征。这种优化的催化剂可用于 1-辛烯与各种芳基胺和烷基胺的加氢氨基烷基化反应,但可以通过具有挑战性的 N-烷基仲胺底物实现显着增强的催化活性。该催化剂提供高达 60 h-1 的转换频率,使用这些亲核胺在大约 20 分钟内以 5 mol% 催化剂负载提供完全转化。包括动力学同位素效应 (KIE) 研究在内的机理研究表明,催化转化受到中间 5 元氮杂金属环的质子分解的限制。哈米特动力学分析表明,催化转化是由富电子胺底物促进的,这些底物能够促进催化转化。这种活性更高的催化剂被证明对后期药物修饰是有效的。