Visible-Light-Promoted [2 + 2 + 2] Cyclization of Alkynes with Nitriles to Pyridines Using Pyrylium Salts as Photoredox Catalysts
作者:Kuai Wang、Ling-Guo Meng、Lei Wang
DOI:10.1021/acs.orglett.7b00292
日期:2017.4.21
regioselective [2 + 2 + 2] cyclization of aromatic alkynes with nitriles is developed for the preparation of 2,3,6-trisubstituted pyridines under visible-light irradiation using a pyrylium salt as the photoredox catalyst. This cycloaddition is achieved through a photooxidative single-electron-transfer process at room temperature and under metal-free conditions. A variety of aromatic alkynes and nitriles
A two-dimensional oxonium-embedded COF with vinylene linkages was synthesized by condensation of a trimethyl-substituted pyrylium with a tritopic aromatic aldehyde derivative, which was readily converted to a neutral pyridine-cored COF by in situ replacing oxonium with nitrogen atoms under the treatment of ammonia.
Electron transfer to excited doublet states. Photoirradiation of 10-methylphenothiazine cation radical perchlorate in solutions of phenylacetylene and p-tolylacetylene in acetonitrile