Delarmelina Maicon, Marelli Enrico, de M Carneiro José Walkimar, Nolan Steven P, Bühl Michael
Universidade Federal Fluminense, Instituto de Química, Niterói, Rio de Janeiro, 24020-141, Brazil.
University of St Andrews, School of Chemistry, North Haugh, St Andrews, Fife, KY16 9ST, Scotland (UK.
Chemistry. 2017 Oct 20;23(59):14954-14961. doi: 10.1002/chem.201703567. Epub 2017 Sep 26.
A new mechanism is proposed for the Ni-catalyzed carboxylation of organoboronates with CO . DFT investigations at the PBE0-D3 level have shown that direct CO addition to the catalysts [Ni(NHC)(Allyl)Cl] (1 , NHC=IMe, IPr, SIPr and IPr*) is kinetically disfavored and formation of the Aresta-type intermediate is unlikely to occur. According to the mechanism proposed here, the carboxylation process starts with addition of the borate species to 1 , followed by transmetalation, CO cycloaddition and carboxylation. The rate-determining step was identified as being the transmetalation process, with computed relative free energy barriers of 34.8, 36.8, and 33.5 kcal mol for 1 , 1 and 1 , respectively.
本文提出了一种镍催化有机硼酸酯与CO羧基化反应的新机制。在PBE0-D3水平上的密度泛函理论（DFT）研究表明，CO直接加成到催化剂[Ni(NHC)(Allyl)Cl]（1，NHC = IMe、IPr、SIPr和IPr*）上在动力学上是不利的，且不太可能形成阿雷斯塔型中间体。根据本文提出的机制，羧基化过程始于硼酸酯物种加成到1上，随后进行金属转移、CO环加成和羧基化反应。速率决定步骤被确定为金属转移过程，计算得出1、1和1的相对自由能垒分别为34.8、36.8和33.5 kcal·mol。
