Meher Naresh Kumar, Verma Piyush Kumar, Geetharani K
Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012, India.
Org Lett. 2023 Jan 13;25(1):87-92. doi: 10.1021/acs.orglett.2c03891. Epub 2023 Jan 3.
Regioselective hydroboration of pyridines to 1,2-dihydropyridines remains a significant challenge for the synthesis of valuable nitrogenous bioactive molecules. Herein, we report a base free ligand-controlled cobalt-catalyzed 1,2-hydroboration of pyridines and quinolines with very low catalyst loading under neat reaction conditions. The choice of sterically demanding N-heterocyclic ligands led to the 1,2-regioselectivity and the scope was demonstrated by the N-heterocycles having a variety of functional groups. The preliminary mechanistic studies corroborate that the two ligands followed a distinct catalytic cycle with Co(I) as an active species.
将吡啶区域选择性硼氢化生成1,2-二氢吡啶，对于合成有价值的含氮生物活性分子而言，仍然是一项重大挑战。在此，我们报道了一种在无碱配体控制下，以极低催化剂负载量，在纯反应条件下实现钴催化吡啶和喹啉的1,2-硼氢化反应。空间位阻较大的N-杂环配体的选择导致了1,2-区域选择性，并且具有各种官能团的N-杂环化合物证明了该反应的适用范围。初步机理研究证实，两种配体与作为活性物种的Co(I)遵循不同的催化循环。
