One‐pot Synthesis of Substituted Pyrazoles from Propargyl Alcohols via Cyclocondensation of in situ‐Generated α‐Iodo Enones/Enals and Hydrazine Hydrate
Huifeng Guo, Qinglin Zhang, Wanyong Pan, Yang Hong, Keke Pei, Jiulong Zhai, Tiantian Li, Zhihai Wang, Yan Wang, Yan Yin
Abstract
Abstract An efficient Bi(OTf) 3 ‐catalyzed transformation of unprotected propargylic alcohols has been developed, affording a general, one‐pot approach to access diverse pyrazoles via sequential iodo‐intercepted Meyer‐Schuster rearrangement, cyclocondensation of NH 2 NH 2 ⋅ H 2 O and α‐iodo enones/enals generated in situ, and iodine elimination. This transformation tolerates a wide range of substrates and is reliable on a large scale. The high yields and convenient experimental operations make it a valuable method for the construction of pyrazole derivatives.
Topics & Concepts
ChemistryHydrazine (antidepressant)PropargylHydratePyrazoleIn situIodineCombinatorial chemistryTransformation (genetics)Propargyl alcoholCatalysisMedicinal chemistryOrganic chemistryBiochemistryChromatographyGeneCatalytic Alkyne ReactionsCatalytic C–H Functionalization MethodsCyclopropane Reaction Mechanisms