Synthetic and mechanistic studies of metal-free transfer hydrogenations applying polarized olefins as hydrogen acceptors and amine borane adducts as hydrogen donors
作者:Xianghua Yang、Thomas Fox、Heinz Berke
DOI:10.1039/c1ob06381b
日期:——
spectroscopy. Deuterium kinetic isotope effects and the traced hydroboration intermediate revealed that the double H transfer process occurred regio-specifically in two steps with hydride before proton transfer characteristics. Studies on substituent effects and Hammett correlation indicated that the rate determining step of the HN transfer is in agreement with a concerted transition state. The very reactive intermediate
极化烯烃的无金属转移氢化(RR'C CEE':R,R'= H或有机基,E,E'= CN或 CO 2我)使用胺硼烷加合物 RR'NH–BH 3(R = R'= H,AB ; R = Me,R'= H,人与生物圈; R = t Bu,R'= H,tBAB; R = R′=我,DMAB通过原位NMR光谱研究作为氢供体的H 2O。氘 动力学同位素效应和所追踪的硼氢化中间体表明,双H转移过程在两个步骤中都发生了区域特异性反应 氢化物质子转移前的特征。对取代基效应和Hammett相关性的研究表明,^ h ñ转移与一致的过渡状态相一致。由AB生成的非常活泼的中间体[NH 2 BH 2 ]通过添加二甲醚被捕集环己烯 进入反应混合物形成 Cy 2 BNH 2。最终产品硼嗪假定(BHNH)3是通过[NH 2 BH 2 ]或其溶剂稳定的衍生物[NH 2 BH 2 ]-(溶剂)脱氢偶联形成的,而不是通过环三硼烷[NH