Alkylation of 1-phenyl-3,5-disubstituted pyrazoles with polyfluorinated aliphatic aldehydes: Properties of 1-phenyl-4-(1-hydroxypolyfluoroalkyl)pyrazole derivatives

Polyfluorinated aliphatic aldehydes react with 1-phenyl-3-methylpyrazole-5-one, 1-phenyl-3-methyl-5-amino (N,N-dimethylaminomethylenamino)pyrazole and 1-phenyl-3-aminopyrazole-5-one at room temperature in the absence of catalyst with formation of 4-(1-hydroxypolyfluoroalkyl)pyrazoles. Dehydration of 4-(1-hydroxypolyfluoroalkyl)pyrazoles with morpholinosulfur trifluoride generates 4-polyfluoroalkylidenepyrazoles, which are active dienophiles and react with 2,3-dimethylbutadiene and cyclopentadiene forming spirocyclic pyrazole derivatives.