Sequence Control in Asymmetric Terpolymerizations of meso‐Epoxides, CO2, and Phthalic Anhydride: Unprecedented Statistical Ester–Carbonate Distributions

• Published in: Angewandte Chemie International Edition Vol. 62; no. 27; pp. e202304943 - n/a
• Main Authors: He, Guang‐Hui, Ren, Bai‐Hao, Wang, Shang, Liu, Ye, Lu, Xiao‐Bing
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 03.07.2023
• Edition: International ed. in English
• Subjects: Aluminum; Asymmetric Ring-Opening Terpolymerization; Asymmetry; Bimetals; Biodegradation; Carbon Dioxide; Catalysts; Copolymerization; Enantiomers; Epoxides; Meso-Epoxides; NMR; Nuclear magnetic resonance; Phthalic anhydride; Polymers; Sequence Control; Statistical Distributions; Statistics; Terpolymerization; Terpolymers; Thermal properties; Thermodynamic properties
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202304943

The statistical terpolymerization of epoxides, CO2 and cyclic anhydrides remains challenging, mainly because epoxide/CO2 and epoxide/anhydride copolymerizations typically proceed at considerably different rates. Herein, we report the syntheses of novel chiral terpolymers with unprecedented statistical distributions of carbonate and ester units (up to 50 % junction units) via the one‐pot reaction of cyclohexene oxide, phthalic anhydride, and CO2 under mild conditions using enantiopure bimetallic aluminum‐complex‐based catalyst systems. Notably, all resulting terpolymers exhibited excellent enantioselectivities (≥96 % ee) that were independent of the carbonate–ester distribution. The statistical compositions of the carbonate and ester units in the resulting terpolymers were determined via 1H and 13C NMR spectroscopies. Furthermore, thermal properties were tuned by altering the ester content of the chiral terpolymer without influencing the enantioselective ring‐opening step involving the meso‐epoxide. This asymmetric terpolymerization methodology is also compatible with a variety of meso‐epoxides to afford the corresponding terpolymers with 17 %–25 % junction units and excellent enantioselectivities (94 %–99 % ee). The present study is expected to provide new guidelines for preparing a broad range of biodegradable polymers with excellent enantioselectivities and adjustable properties. The asymmetric terpolymerizations of meso‐epoxides, CO2, and phthalic anhydride mediated by dinuclear aluminum catalysts with multiple stereogenic centers delivered unprecedented statistical ester–carbonate distributions and excellent enantioselectivities.