Studies on the synthesis of heterocyclic compounds. Part IX. Action of N,N‐dimethylformamide dimethylacetal on some oximino‐β‐dicarbonyl compounds

Abstract

Abstract3‐Oximino‐2,4‐pentanedione (1) and ethyl 2‐oximino‐3‐oxobutanoate (6) reacted with N,N‐dimethylformamide dimethylacetal (DFDA) to give 1,7‐bisdimethylamino‐3,5‐dioxo‐4‐methoximinohepta‐1,6‐diene (4) and ethyl 5‐dimethylamino‐2‐methoximino‐3‐oxo‐4‐pentenoate (8), respectively. When compounds 4 and 8 were treated with hydrazine hydrate, they gave O‐methyldipyrazol‐3(5)‐ylketoxime (5) and ethyl 2‐methoximino‐3(5)‐pyrazolylethanoate (9) together with its corresponding hydrazide 10, respectively. Upon action of DFDA on 3‐oximino‐2,4‐pentanedione (1) at ‐20° an explosive crystalline product was obtained. On the other hand, the reaction of 3‐acetoximino‐2,4‐pentanedione (11) with DFDA at ‐20° afforded a product which in ethanol solution, spontaneously deacetylated to give 1‐dimethylamino‐3,5‐dioxo‐4‐oximinohexa‐1‐ene (13). The structures of all the new compounds were assigned on the basis of satisfactory analytical and spectroscopic data.