title: Visible-Light-Mediated Oxidative Dimerization of Arylalkynes in the Open Air: Stereoselective Synthesis of (Z)-1,4-Enediones.
abstract: An organic photoredox catalytic one-pot protocol is developed for the highly stereoselective synthesis of (Z)-1,4-enediones. The reaction starts directly from alkyne precursors, using 4-(4-cyanophenyl)-2,6-diphenylpyrylium tetrafluoroborate (CN-TPT) as an efficient photosensitizer and dioxygen in the air as a green oxidant. A Csp-Cspoxidative coupling/[4 + 2] cyclization (with dioxygen)/fragmentive isomerization cascade mechanism was proposed. The predominant formation of (Z)-1,4-enediones is attributed to the efficient visible-light illumination from blue LEDs, along with possible energy transfer from the photosensitizer CN-TPT to the E-isomers.
authors.affiliation: Department of Chemistry, Northeast Normal University , Changchun 130024, China.
authors.forename: Donglei
authors.initials: D
authors.lastname: Wei
authors.affiliation: College of Chemistry, Liaoning University , Shenyang 110036, China.
authors.forename: Fushun
authors.initials: F
authors.lastname: Liang