Direct nitration of aldehyde arylhydrazones and the use of the products in the synthesis of some heterocyclic compounds

Direct nitration of substituted benzaldehyde p ‐nitrophenylhydrazones 1 gave α‐nitroarylidene‐ p ‐nitrophenylhydrazines 2 . Reactions of 2 with nucleophiles result in displacement of the nitrite. Treatment of 2 with potassium thiocyanate gave 5‐imino‐1,3,4‐Δ 2 ‐thiadiazolines 10 . Reactions of 2 with carbanions of active methylene compounds yielded the pyrazole derivatives 15–20 . 1,3‐Dipolar cycloadditions of 2 onto acrylonitrile and benzalacetophenone afforded the expected cycloadducts 21 and 22 , respectively.