Bifunctional catalysts based on m-phenylene-bridged porphyrin dimer and trimer platforms: synthesis of cyclic carbonates from carbon dioxide and epoxides

Chihiro Maeda; Tomoya Taniguchi; Kanae Ogawa; Tadashi Ema

doi:10.1002/anie.201409729

Bifunctional catalysts based on m-phenylene-bridged porphyrin dimer and trimer platforms: synthesis of cyclic carbonates from carbon dioxide and epoxides

Angew Chem Int Ed Engl. 2015 Jan 2;54(1):134-8. doi: 10.1002/anie.201409729. Epub 2014 Nov 4.

Authors

Chihiro Maeda¹, Tomoya Taniguchi, Kanae Ogawa, Tadashi Ema

Affiliation

¹ Division of Chemistry and Biotechnology, Graduate School of Natural Science and Technology, Okayama University, Tsushima, Okayama 700-8530 (Japan). cmaeda@okayama-u.ac.jp.

PMID: 25370986
DOI: 10.1002/anie.201409729

Abstract

Highly active bifunctional diporphyrin and triporphyrin catalysts were synthesized through Stille coupling reactions. As compared with a porphyrin monomer, both exhibited improved catalytic activities for the reaction of CO2 with epoxides to form cyclic carbonates, because of the multiple catalytic sites which cooperatively activate the epoxide. Catalytic activities were carefully investigated by controlling temperature, reaction time, and catalyst loading, and very high turnover number and turnover frequency were obtained: 220 000 and 46 000 h(-1) , respectively, for the magnesium catalyst, and 310 000 and 40 000 h(-1) , respectively, for the zinc catalyst. Results obtained with a zinc/free-base hybrid diporphyrin catalyst demonstrated that the Br(-) ions on the adjacent porphyrin moiety also function as nucleophiles.

Keywords: carbon dioxide fixation; cyclic carbonates; homogeneous catalysis; porphyrinoids; zinc.