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‐dimethylpyrazol‐1‐yl)acetone 4 with aromatic diazonium salts afforded the corresponding arylhydrazones 5a,b that were converted into pyridazines 6a,b and 8 via condensation with active methylene nitriles and dimethylformamide dimethylacetal, respectively. Condensation of 4 with 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, benzyl‐idenemalononitrile to yield a variety of substituted new pyrazoles.