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New Practical Synthesis of Indazoles via Condensation of o -Fluorobenzaldehydes and Their O -Methyloximes with Hydrazine

2006; American Chemical Society; Volume: 71; Issue: 21 Linguagem: Inglês

10.1021/jo0613784

1520-6904

K. A. LUKIN, Margaret C. Hsu, Dilinie P. Fernando, M. Robert Leanna,

Fluorine in Organic Chemistry

The reaction of o-fluorobenzaldehydes and their O-methyloximes with hydrazine has been developed as a new practical synthesis of indazoles. Utilization of the methyloxime derivatives of benzaldehydes (in the form of the major E-isomers) in this condensation effectively eliminated a competitive Wolf-Kishner reduction to fluorotoluenes, which was observed in the direct preparations of indazoles from aldehydes. Reaction of Z-isomers of methyloximes with hydrazine resulted in the formation of 3-aminoindazoles via a benzonitrile intermediate.