Reaching Green: Heterocycle Synthesis by Transition Metal-Catalyzed C-H Functionalization in Sustainable Medium.

Catalytic C-H functionalization has emerged as an efficient alternative to traditional coupling reactions. However, some of these reactions depend on environmentally harmful solvents, weakening the overall green nature of these methods. As organic processes consume large amount of solvents, the use of less harmful solvents enhance the sustainability of these reactions.

Hydroarylations by cobalt-catalyzed C-H activation.

As an earth-abundant first-row transition metal, cobalt catalysts offer a broad range of economical methods for organic transformations via C-H activation. One of the transformations is the addition of C-H to C-X multiple bonds to afford alkylation, alkenation, amidation, and cyclization products using low- or high-valent cobalt catalysts. This hydroarylation is an efficient approach to build new C-C bonds in a 100% atom-economical manner.

Ligand-Controlled Divergent C-H Functionalization of Aldehydes with Enynes by Cobalt Catalysts.

We describe a highly step and atom economical cobalt-catalyzed cyclization of 1,6-enynes with aldehydes to synthesize functionalized pyrrolidines and dihydrofurans with high chemo- and stereoselectivity. The catalytic reaction plausibly proceeds via the cobaltacycle intermediate generated from the reaction of enyne substrate with cobalt catalyst, followed by switchable C-H functionalization of weakly coordinating aldehydes depending on the electronic nature of the ligand.

Cobalt-catalyzed hydroarylative cyclization of 1,6-enynes with aromatic ketones and esters via C-H activation.

A highly chemo- and stereoselective cobalt-catalyzed hydroarylative cyclization of 1,6-enynes with aromatic ketones and esters to synthesize functionalized pyrrolidines and dihydrofurans is described. A mechanism involving cobaltacycle triggered C-H activation of aromatic ketones and esters was proposed.