Studies with functionally substituted N-alkylazoles: The reactivity of 1-(3,5-dimethylpyrazol-1-yl)acetone towards electrophilic reagents

The reaction of 1-(3,5-dimethylpyrazo1-1-yl)acetone 4 with aromatic diazoni um salts afforded the corresponding arylhydrazones 5a,b that were converted into pyridazines 6a,b and 8 via condensation with active methylene nitrile s and dimethylformamide dimethylacetal, respectively. Condensation of 4 wit h phenylhydrazine afforded the phenylhydrazone 10, which could be converted into the indolylpyrazole 11 on treatment with ethanolic hydrochloric acid. Compound 4 also reacted with nitrous acid, benzylidenemalononitrile to yie ld a variety of substituted new pyrazoles.