Homogeneous catalytic hydrogenation of carbonyl groups is a synthetically useful and widely applied organic transformation. Sustainable chemistry goals require replacing conventional noble transition metal catalysts for hydrogenation by earth-abundant base metals. Herein, we report how a practical in situ catalytic system generated by easily available pincer NHC precursors, CoCl₂, and a base enabled efficient and high-yielding hydrogenation of a broad range of ketones and aldehydes (over 50 examples and a maximum turnover number [TON] of 2,610). This is the first example of NHC-Co-catalyzed hydrogenation of C=O bonds using flexible pincer NHC ligands consisting of a N-H substructure. Diastereodivergent hydrogenation of substituted cyclohexanone derivatives was also realized by fine-tuning of the steric bulk of pincer NHC ligands. Additionally, a bis(NHCs)-Co complex was successfully isolated and fully characterized, and it exhibits excellent catalytic activity that equals that of the in-situ-formed catalytic system.

羰基的均相催化加氢是合成上有用且广泛应用的有机转化。可持续的化学目标要求用富含地球的贱金属代替传统的贵金属过渡金属催化剂进行氢化反应。在这里，我们报告如何由容易获得的钳NHC前体CoCl ₂生成实际的原位催化系统，以及一种碱，可以高效，高产率地氢化各种酮和醛（超过50个实例，最大周转数[TON]为2,610）。这是使用由NH亚结构组成的挠性NHC配体进行的NHC-Co催化的C = O键加氢的第一个例子。还可以通过微调钳型NHC配体的空间体积来实现取代的环己酮衍生物的非对映异构氢化。另外，成功地分离并完全鉴定了双（NHCs）-Co配合物，它显示出与原位形成的催化体系相同的出色催化活性。