Copper Catalyzed C−H Activation

Activation of C-H bonds and their application in cross coupling chemistry has received a wider interest in recent years. The conventional strategy in cross coupling reaction involves the pre-functionalization step of coupling reactants such as organic halides, pseudo-halides and organometallic reagents. The C-H activation facilitates a simple and straight forward approach devoid of pre-functionalization step. This approach also addresses the environmental and economical issues involved in several chemical reactions. In this account, we have reported C-H bond activation of small organic molecules, for example, formamide C-H bond can be activated and coupled with β-dicarbonyl or 2-carbonyl substituted phenols under oxidative conditions to yield carbamates using inexpensive copper catalysts. Phenyl carbamates were successfully synthesized in moderate to good yields by cross dehydrogenative coupling (CDC) of phenols with formamides using copper catalysts in presence of a ligand. We have also prepared unsymmetrical urea derivatives by oxidative cross coupling of formamides with amines using copper catalysts. Synthesis of N,N-dimethyl substituted amides, 5-substituted-γ-lactams and α-acyloxy ethers was carried out from carboxylic acids using recyclable CuO nanoparticles. Copper nanoparticles afforded N-aryl-γ-amino-γ-lactams by oxidative coupling of aromatic amines with 2-pyrrolidinone. Reusable transition metal HT-derived oxide catalyst was used for the synthesis of N,N-dimethyl substituted amides by the oxidative cross-coupling of carboxylic acids and substituted benzaldehydes. Overview of our work in this area is summarized.