Dual Kinetic Control of Polycarbonate Sequences via Breaking Catalysis Symmetry Using Dual Biomimetic Organoboron Catalysts

Abstract

Biomimetic catalysis is extensively used in chemical synthesis targeting to achieve satisfactory reactivities. However, artificial catalysts possessing outstanding sequence controllability over macromolecular structures that could be precisely achieved in nature remain scarce, especially in the preparation of complex macromolecules featuring kinetically trapped structures. Herein, we report a dual biomimetic catalyst design for precise sequence regulation in kinetically controlled CO₂/epoxide copolymerization. The as-synthesized dissymmetric organoboron catalysts possess dissymmetric catalysis microenvironments, which differentiate the transfer rates of polymer alkoxy anions between the two boron centers, thus enabling precise sequence regulation. Consequently, a high −ABB–/–AB– ratio of 92% was achieved, up to 3.3 times that of analogous symmetric catalysts (Nat. Synth. 2022, 1, 892–901). Detailed mechanistic studies reveal that dual kinetic modulations are responsible for sequence regulation. This catalyst design tactic should inspire effective catalyst designs for precise chemical transformations.