Transition-metal-catalyzed C‒C bond formation reaction by uniting readily available π-components is an attractive strategy to synthesis biologically important compounds in a single operation with high atom-efficacy. Particularly, asymmetric synthesis and C H bond activation reactions are competent method to synthesis biologically important compounds in a highly regio- and stereoselective manner. In this regard, this thesis describes ten new reactions that focus on the asymmetric addition of arylboronic acids with aldehydes, bicyclic alkenes, which were successfully achieved by tuning different kinds of chiral ligands in the presence of air stable cobalt catalyst system. The C H functionalization of arylboronic acids with heteroarenes and N-methoxybenzamides to afford various functionalized biaryls. On the other hand multiple C H activations of N-methoxybenzamides with simple arenes and alkenes afforded biologically active phenanthridinone and isoindolinone derivatives in one-pot manner. For better understanding, I divided this thesis into seven chapters. The first three chapters describe about cobalt-catalyzed addition reactions of aldehydes and bicyclic alkenes with organoboronic acids. The fourth chapter describe about cobalt-catalyzed direct arylation reaction of heteroarenes with organoboronic acids. The next two chapters deal with palladium-catalyzed C-H activation reactions of N-methoxybenzamides with simple arenes and alkenes. The final chapter describe about the dual C H activations of N-methoxybenzamides with arylboronic acids using rhodium(III) as the catalyst.