DMSO as a C<sub>1</sub> Source for [2 + 2 + 1] Pyrazole Ring Construction via Metal-Free Annulation with Enaminones and Hydrazines
Haijin Guo, Lihong Tian, Yunyun Liu, Jie‐Ping Wan
Abstract
A cascade reaction between enaminones, hydrazines, and dimethyl sulfoxide (DMSO) for the synthesis of 1,4-disubstituted pyrazoles catalyzed by molecular iodine in the presence of Selectfluor has been realized. DMSO plays a dual role as the C1 source and the reaction medium. In addition, the synthesis of 1,3,4-trisubstituted pyrazoles using aldehydes as alternative C1 building blocks has also been achieved.
Topics & Concepts
ChemistryAnnulationPyrazoleRing (chemistry)Dimethyl sulfoxideCombinatorial chemistryCascade reactionIodineMedicinal chemistryCatalysisOrganic chemistrySynthesis and Characterization of PyrrolesSynthesis and Biological EvaluationCatalytic C–H Functionalization Methods