Synthesis of 2-Aminopyridines via Cobalt-Catalyzed Cycloaddition of Diynes with N-Substituted and N-Unsubstituted Cyanamides

Reactivity of nitriles in a CoCl2-6H(2)O/dppe/Zn-catalyzed diyne-nitrile cycloaddition was explored through the competitive reactions of a diyne with two different nitriles, and it was found that cyanamides are good substrates, and the reaction yielded 2-aminopyridines. Notably, N-unsubstituted cyanamide (H2N-CN) could be used for the reaction with 1,6-diynes to afford the corresponding N-unsubstituted 2-aminopyridines, which cannot be prepared via other catalytic reactions and are versatile intermediates for further transformations such as the synthesis of 2-substituted pyridines and 6,7-annulated imidazo[1,2-a]pyridines.

Automated summary

The reactivity of nitriles in a CoCl2-6H(2)O/dppe/Zn-catalyzed diyne-nitrile cycloaddition was studied. It was found that cyanamides are good substrates and result in the formation of 2-aminopyridines. Notably, N-unsubstituted cyanamide (H2N-CN) can react with 1,6-diynes to produce N-unsubstituted 2-aminopyridines, which cannot be obtained through other catalytic reactions and serve as versatile intermediates for further transformations.