Among chiral macrocycles 1 synthesized, 1m with the 3,5-bis(trifluoromethyl)phenylethynyl group was the best organocatalyst for the enantioselective synthesis of cyclic carbonates from disubstituted or monosubstituted epoxides and CO2. The X-ray crystal structure of 1m revealed a well-defined chiral cavity with multiple hydrogen-bonding sites that is suitable for the enantioselective activation of
Chiral Bifunctional Metalloporphyrin Catalysts for Kinetic Resolution of Epoxides with Carbon Dioxide
作者:Chihiro Maeda、Mayato Mitsuzane、Tadashi Ema
DOI:10.1021/acs.orglett.9b00447
日期:2019.3.15
triazolium halide units were synthesized as bifunctional catalysts for kinetic resolution of epoxides with CO2. Several catalysts were screened by changing the linker length and nucleophilic counteranions, and the optimized catalyst accelerated the enantioselective reaction at ambient temperature to produce optically active cyclic carbonates and epoxides.
Kinetic Resolution of Epoxides with CO
<sub>2</sub>
Catalyzed by a Chiral‐at‐Iridium Complex
作者:Jie Qin、Vladimir A. Larionov、Klaus Harms、Eric Meggers
DOI:10.1002/cssc.201802049
日期:2019.1.10
Chiral‐at‐metal bis‐cyclometalated iridium(III) complexes are introduced as a new class of chiral catalysts for the reaction of epoxides with CO2 to form cyclic carbonates under conditions of kineticresolution. Reactions are typically performed at room temperature in the presence of 1 mol % of iridium catalyst and 1.5 mol % of tetraethylammonium bromide as the nucleophilic cocatalyst to provide selectivity