Photoinduced Substitution Reaction Initiated by Electron-Transfer. Photochemical Reaction of 2,3-Dichloro-1,4-naphthoquinone with Thiophenes

Abstract

Photochemical reaction of 2,3-dichloro-1,4-naphthoquinone (1) with thiophenes 2 afforded 2-chloro-3-(2-thienyl)-1,4-naphthoquinones. The reaction might be initiated by the photoelectron transfer from 2 to 1, resulting in the formation of combined products via recombination of the formed ion radicals 1\ewdot and 2\underset.+ by accompanying elimination of chloro and hydro radicals. In the photoreaction, reactivity of 2 was estimated from the observed oxidation potentials of 2 and the calculated electron densities in 2\underset.+.