Abstract Addition of methylhydrazine to a variety of haloalkyl-substituted α, β-unsaturated esters gives 1, 5-disubstituted 3-hydroxypyrazoles, in contrast to the more common synthesis from β-ketoesters, which gives 1, 3-disubstituted 5-hydroxypyrazoles. This reaction is used to prepare several novel pyrazoles bearing haloalkyl substituents. Criteria for assignment of structures have been developed based on physical and spectroscopic ...
