Reactivity Profiles of Diazo Amides, Esters, and Ketones in Transition-Metal-Free C–H Insertion Reactions
作者:Sarah E. Cleary、Xin Li、Li-Cheng Yang、K. N. Houk、Xin Hong、Matthias Brewer
DOI:10.1021/jacs.8b12420
日期:2019.2.27
Vinyl cations derived from diazo ketones participate in transition-metal-free C-H insertion reactions, but the corresponding amide and ester analog exhibit divergent reactivity profiles. Whereas cations formed from diazo ketones undergo a rearrangement and C-H insertion sequence, those from diazo amides do so less efficiently and tend to be competitively trapped before the insertion step occurs. Diazo
源自重氮酮的乙烯基阳离子参与无过渡金属的 CH 插入反应,但相应的酰胺和酯类似物表现出不同的反应性特征。虽然由重氮酮形成的阳离子经历重排和 CH 插入序列,但来自重氮酰胺的阳离子的效率较低,并且往往在插入步骤发生之前被竞争性捕获。重氮酯经历了几个重排步骤并且无法插入。DFT 计算表明,这种差异源于两个因素:相邻羰基氧对初始形成的乙烯基阳离子的静电稳定水平不同,以及酮和酰胺系统对 CH 插入的预变形。计算数据与实验结果非常吻合,