Polycondensation of methacrylates: auto-tandem organocatalysis using N-heterocyclic carbenes

The first polycondensations of methacrylates have been realized by auto-tandem N-heterocyclic carbene (NHC) catalysis comprising transesterification and tail-to-tail dimerization. The single NHC catalyst promoted self-polycondensation of hydroxy-functionalized methacrylates and direct polycondensation of n-butyl methacrylate (nBMA) with diols to synthesize new unsaturated polyesters. The self-polycondensation efficiently produced polyesters in high yields. The short-time polymerization indicates that the transesterification and dimerization proceed simultaneously. The direct polycondensation can be used to readily produce a variety of polyesters by changing the diols under optimized conditions. Even in the presence of excess alcohols, the NHC efficiently catalyzes the dimerization through the umpolung of methacrylates combined with the activation of alcohols for transesterification.