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Updated: Aug 10, 2026
Chemoselective Preparation of 1-Iodoalkynes, 1,2-Diiodoalkenes, and 1,1,2-Triiodoalkenes Based on the Oxidative Iodination of Terminal Alkynes
Published on: September 12, 2018
Revised structure of a purported 1,2-dioxin: a combined experimental and theoretical study
Eric Block1, Zhixing Shan, Richard S Glass
1Department of Chemistry, State University of New York at Albany, 12222, USA. eb801@albany.edu
Abstract:
3,6-Bis(p-tolyl)-1,2-dioxin (1g) was suggested by Shine and Zhao as a product in an electron-transfer (ET) photochemical reaction. This photoproduct is instead shown to be (E)-1,4-di-p-tolylbut-2-ene-1,4-dione ((E)-4a). Ab initio and DFT calculations indicate that ring-closed 1,2-dioxin is thermodynamically far less stable than open-chain but-2-ene-1,3-dione. These calculations indicate that (E)-4a is formed via the cation radical of 1g, which sequentially isomerizes to a novel sigma-radical with an O,O 3e bond [(Z)-4a](+)(*), undergoes ET to give (Z)-4a, and then photoisomerizes to (E)-4a.
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