Chiral Polyureas Derived Cinchona Alkaloids: Highly Efficient Bifunctional Organocatalysts for the Asymmetric Michael Addition Reaction

Abstract

Repetitive Mizoroki-Heck (MH) coupling polymerization was used to create novel chiral polyureas with cinchona alkaloids in the main chain. Apart from two-component polycondensation of cinchona urea dimers with diiodobenzene via MH reaction conditions, some chiral polyureas were easily polymerized under self polycondensation to yield the chiral polymers. The asymmetric Michael addition reaction was successfully carried out using chiral polymers derived cinchona urea. Interestingly, phenolic-based chiral polymers served as heterogeneous catalysts for the enantioselective Michael reaction, with high catalytic activity and excellent enantioselectivities (up to 99 % ee). These polymeric catalysts were also stable, and they could be recycled and reused.