Metal-Free Synthesis of 2<i>H</i>-Indazole Skeletons by Photochemistry or Thermochemistry
Gan Zhang, Yicheng Zhang, Pinhua Li, Chao Zhou, Min Wang, Lei Wang
Abstract
A simple and tuned synthesis of a 2 H -indazole skeleton under metal-free conditions was developed. Under visible-light irradiation at room temperature, 2-((aryl/alkyl/H)ethynyl))aryltriazenes reacted with arylsulfinic acids to afford 3-functionalized 2H -indazoles without extra photocatalyst via an electron donor–acceptor complex. In the presence of arylsulfinic acid, 2-(ethynyl)aryltriazenes underwent an intramolecular oxidation/cyclization to provide 2 H -indazole-3-carbaldehydes at 50 °C in air.
Topics & Concepts
ThermochemistryIndazoleChemistryMetalPhotochemistryComputational chemistryInorganic chemistryOrganic chemistrySulfur-Based Synthesis TechniquesCatalytic C–H Functionalization MethodsRadical Photochemical Reactions