Moderately Oxidizing Thioxanthylium Organophotoredox Catalysts for Radical-Cation Diels-Alder Reactions

Kenta Tanaka; Mami Kishimoto; Yuta Tanaka; Yusuke Kamiyama; Yosuke Asada; Mayumi Sukekawa; Naoya Ohtsuka; Toshiyasu Suzuki; Norie Momiyama; Kiyoshi Honda; Yujiro Hoshino

doi:10.1021/acs.joc.1c02972

Moderately Oxidizing Thioxanthylium Organophotoredox Catalysts for Radical-Cation Diels-Alder Reactions

J Org Chem. 2022 Mar 4;87(5):3319-3328. doi: 10.1021/acs.joc.1c02972. Epub 2022 Feb 10.

Authors

Affiliations

¹ Graduate School of Environment and Information Sciences, Yokohama National University, Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan.
² Institute for Molecular Science, Okazaki, Aichi 444-8787, Japan.
³ SOKENDAI (The Graduate University for Advanced Studies), Okazaki, Aichi 444-8787, Japan.

PMID: 35142514
DOI: 10.1021/acs.joc.1c02972

Abstract

Moderately oxidizing thioxanthylium photoredox catalysts that operate under irradiation with green light have been developed. These catalysts exhibit relatively moderate excited-state reduction potentials [E_1/2(C*/C^•-) = 1.75-1.94 V vs saturated calomel electrode (SCE)] and can efficiently promote radical-cation Diels-Alder reactions under irradiation with green light. Interestingly, β-halogenostyrenes (E_p/2 = 1.57-1.61 V vs SCE) are well tolerated, affording synthetically useful halocyclohexenes.