Transition metal catalyzed C−C activation has been emerging from organometallic curiosity to useful synthetic tools in recent year. In particular, this method has great potential on constructing bridged rings systems in natural products and polymer degradation. In this thesis, introduction of the background and recent advances in this area was included. Besides, we also demonstrated our efforts towards the total synthesis of pencibilaenes using "C−C/C−H" strategy. The development of transition metal catalyzed unstrained C(aryl)−C(alkyl) bonds in 2,2'-methylenediphenols and ortho-methyl phenols was also enclosed.