Metal-Free Tandem Oxidative Cyclization for the Synthesis of 1,2-Dihydropyridazines and Pyrazoles
Dongping Cheng, Yinqiang Shen, Ziliang Wu, Xiaoliang Xu, Jizhong Yan
Abstract
Mediated by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), a novel oxidative coupling of hydrazones and 1,3-diarylpropenes has been disclosed to generate appealing β,γ-unsaturated hydrazones, which further undergo 5-exo-trig or 6-endo-trig cascade cyclization to give the respective 1,2-dihydropyridazines or pyrazoles selectively under metal-free conditions. The mechanisms of the coupling and subsequent cyclization are proposed.
Topics & Concepts
ChemistryTandemOxidative coupling of methaneOxidative phosphorylationCascadeCascade reactionCoupling (piping)MetalHydrazoneCombinatorial chemistryStereochemistryOrganic chemistryCatalysisBiochemistryChromatographyMechanical engineeringEngineeringComposite materialMaterials scienceCatalytic C–H Functionalization MethodsSynthesis and Biological EvaluationOxidative Organic Chemistry Reactions