A general and expedient amination of alcohols catalysed by a single-site (NN)Co(ii)-bidentate complex under solventless conditions

Here we designed and synthesized a NN-CoII bidentate complex and efficiently used it for general and expedient amination of alcohols under benign, solventless conditions. Both primary (including unactivated aliphatic) alcohols and sterically hindered secondary alcohols exhibited very good reactivity and provided diverse amines with good substrate scope (88 examples; up to 95% yields) and excellent functional group tolerance (methoxy, thiomethoxy, phenoxy, trifluoromethyl, amino, alcoholic and halides including bromo and iodo groups). Furthermore, a sequential bis-N-alkylation of diamines was also demonstrated. It was observed that the pyrazole moiety in the ligand backbone plays a crucial role in the amination reaction. Very interestingly, the reusability of the present homogeneous cobalt catalyst was successfully demonstrated.

Automated summary

We designed and synthesized a NN-CoII bidentate complex and used it for the amination of alcohols under mild and solventless conditions. The complex exhibited good reactivity towards both primary and sterically hindered secondary alcohols, providing high yields of amines. The pyrazole moiety in the ligand played a crucial role in the reaction. Furthermore, we demonstrated the reusability of the complex as a homogeneous cobalt catalyst.