Stereoconvergent Polymerization Driven by Catalytic Racemization

Kinetic-resolution polymerization (KRP), which represents an efficient method for synthesizing enantiopure polymers through the selective reaction of one enantiomer, is inherently limited by a maximum theoretical yield of 50%. In addition, the continuously changing ratio of the two enantiomeric isomers leads to the reduction in stereoregularity of the resulting polymers, particularly as the conversion approaches 50%. To overcome these limitations, we employed rapid racemization to achieve efficient dynamic kinetic resolution polymerization (DKRP), which produces enantioenriched polymers from racemic mixtures in yields of up to 100%. An orthogonal catalytic system comprising a Lewis acid-base pair (tris(perfluorophenyl)borane and N,N-dimethylbutylamine) along with a chiral catalytic complex ((R)-SalBinamAl) were discovered to effectively promote the DKRP of racemic β-propiothiolactones, giving an enantiomeric excess of up to 96% for the (R)-configuration with a conversion of 100%. This strategy overcomes the yield limitation observed in traditional kinetic resolutions. Moreover, this work represents the first example of a catalytic racemization-driven stereoconvergent ring-opening polymerization process, further validating the feasibility of achieving 100% yield in the precise synthesis of enantiopure polymers from racemic monomers.