Rhodium-Catalyzed Silylative and Germylative Cyclization with Dehydrogenation Leading to 9-Sila- and 9-Germafluorenes: A Combined Experimental and Computational Mechanistic Study
作者:Masahito Murai、Ryo Okada、Sobi Asako、Kazuhiko Takai
DOI:10.1002/chem.201701579
日期:2017.8.10
rate constant of dehydrogenative germylation was greater than that of dehydrogenative silylation. Competitive reactions in the presence of 3,3‐dimethyl‐1‐butene indicated that the ratio of dehydrogenative metalation and hydrometalation was affected by reaction temperature when a hydrosilane or hydrogermane precursor was used. Further mechanistic insights of oxidant‐free dehydrogenative silylation, including
化学计量的氧化剂被广泛用作CH键的脱氢甲硅烷基化反应中的促进剂(氢受体)。但是,本研究表明,即使没有氢受体,带脱氢的甲硅烷基化和杀菌环化也可以有效进行。[RhCl(cod)] 2和PPh 3的组合与我们之前的报告相比,对两种转化均有效,并且降低了反应温度。对反应的监测表明,两个转化都具有早期的诱导期,并且脱氢胚芽化的速率常数大于脱氢甲硅烷基化的速率常数。在3,3-二甲基-1-丁烯存在下的竞争反应表明,当使用氢化硅烷或氢化锗烷前体时,脱氢金属化和加氢金属化的比例受反应温度的影响。通过密度泛函理论研究获得了无氧化剂脱氢甲硅烷基化的更多机理见解,包括这些独特反应性的起源。