CHAPTER 6. Bimetallic Complex Mediated Meso-epoxide Desymmetrization Copolymerization

The desymmetrization copolymerization of meso-epoxides with achiral nucleophiles mediated by chiral reagents or catalysts is an efficacious synthetic strategy for preparing optically active polymers with two contiguous (R,R)- or (S,S)-configurational stereogenic centers. This chapter describes in general terms the catalytic polymerization methodology regarding the use of meso-epoxides in desymmetrization copolymerization promoted by multichiral induction and bimetallic synergistic effects for achieving both high activity and enantioselectivity. The major focus will be on the most successful catalyst systems based on enantiopure bimetallic complexes in recent years and the preferred chiral ligand frameworks leading to elevated reactivity and enantioselectivity in meso-epoxide desymmetrization copolymerization reactions, including enantioselective synthesis of polycarbonates from carbon dioxide, poly(thiocarbonate)s from carbonyl sulfide, and polyesters from cyclic anhydrides.