Chelation-Assisted Rhodium-Catalyzed Alkylation of a 1-Arylpyrazole C-H Bond with Cyclopropanols

A general and efficient rhodium-catalyzed ortho-alkylation of N-arylpyrazoles has been accomplished with cyclopropanols as coupling partners. The reaction involves cleavage of both a C-H bond of the arene and a C-C bond of the cyclopropanol, and it offers access to a diversity of substituted 1-(ortho-alkylaryl)-1H-pyrazoles in good to excellent yields. In addition, nonsymmetrical dialkylation and a preliminary mechanistic investigation are also discussed.