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Report | Regular issue | Vol 23, No. 4, 1985, pp.943-951
Published online, 1st January, 1970
DOI: 10.3987/R-1985-04-0943
The Sequential Lithiation of 1-Phenylpyrazoles

Ronald G. Micetich, Verne Baker,* Paul Spevak, Tse W. Hall, and Baljit K. Bains

*Faculty of Pharmacy , University of Alberta, Edmonton, Alberta T6G, 2N8, Canada

Abstract

1-Phenylpyrazole is lithiated exclusively at the C-5 position. Suitable 5-substituted 1-phenylpyrazoles undergo lithiation at the ortho position of the phenyl ring. 5-Thiomethyl-1-(o-tolyl)pyrazole is laterally lithiated at the ortho methyl group. In the case of 5-methoxymethyl-1-phenylpyrazole, lithiation occurs at both the C-5 methylene group and the ortho position of the phenyl ring with n-butyllithium, but essentially exclusive lithiation occurs at the C-5 methylene group with LDA.