Synthesis of 1,2-Dihydropyridines Catalyzed by Well-Defined Low-Valent Cobalt Complexes: C–H Activation Made Simple

A convenient one-pot system has been developed, allowing the synthesis of highly substituted dihydropyridines via a C–H activation/6π-electrocyclization pathway. The reaction proceeds with high regioselectivity, and we disclose the first example of isolated dihydropyridines lacking substitution in the 2 position. Moreover, the use of a simple well-defined low-valent cobalt complex without the need for reducing agents or additives in combination with computational studies provides a clearer insight into the C–H activation pathway than was previously reported.