Recent progress of catalytic polymerization for controlling polymer topology.

Catalysis continues to spark new imagination and excitement of synthetic chemists. Discovery of new catalytic processes often makes seemingly impossible transformations proceed magically at high efficiency. In modern polymer synthesis, an exciting direction in recent years is the development of transition-metal-catalyzed polymerizations for controlling polymer topology. In this Focus Review, we highlight a few recent examples for catalytic syntheses of polyolefins having cyclic, block, and dendritic topologies, respectively. These examples showcase the power and efficiency of transition-metal catalysis for accessing various polymer topologies ranging from simple cyclic to complex globular dendritic polymers.