Max-Planck-Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470, Mülheim an der Ruhr, Germany.
Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Worringer Weg 2, 52074, Aachen, Germany.
Nat Commun. 2018 Oct 30;9(1):4521. doi: 10.1038/s41467-018-06831-9.
Reductive functionalization of the C=O unit in carboxylic acids, carbonic acid derivatives, and ultimately in carbon dioxide itself is a challenging task of key importance for the synthesis of value-added chemicals. In particular, it can open novel pathways for the valorization of non-fossil feedstocks. Catalysts based on earth-abundant, cheap, and benign metals would greatly contribute to the development of sustainable synthetic processes derived from this concept. Herein, a manganese pincer complex [Mn(PhPCHSiMe)NH(CO)Br] (1) is reported to enable the reduction of a broad range of carboxylic acids, carbonates, and even CO using pinacolborane as reducing agent. The complex is shown to operate under mild reaction conditions (80-120 °C), low catalyst loadings (0.1-0.2 mol%) and runs under solvent-less conditions. Mechanistic studies including crystallographic characterisation of a borane adduct of the pincer complex (1) imply that metal-ligand cooperation facilitates substrate activation.
羧酸、碳酸衍生物，最终是二氧化碳本身的 C=O 单元的还原官能化是一项具有重要意义的挑战性任务，对于有价值化学品的合成至关重要。特别是，它可以为非化石原料的增值开辟新途径。基于丰富、廉价且无害的金属的催化剂将极大地促进从这一概念衍生的可持续合成工艺的发展。本文报道了一种锰钳形配合物 [Mn(PhPCHSiMe)NH(CO)Br]（1），它可以使用频哪醇硼烷作为还原剂还原广泛的羧酸、碳酸盐，甚至 CO。该配合物在温和的反应条件（80-120°C）、低催化剂负载（0.1-0.2 mol%）和无溶剂条件下运行。包括钳形配合物（1）的硼烷加合物的晶体结构特征在内的机理研究表明，金属-配体协同作用促进了底物的活化。
