Synthesis of pyrazoles and oxyquinoxalines from 2,4‐dioxohexenoales

Condensation of ethyl 2,4‐dioxo‐6‐phenylhex‐5‐enoates (I; R = H, I; R = Me, I, R = Ph) with various hydrazines yielded ethyl 5‐styrylpyrazole‐3‐carboxylates (III), which were hydrolyzed to the acids (IV), and ozonized to 5‐keto pyrazole esters (VI) and acids (VII). Reduction of the 5‐formylpyrazoles (VI; R = II) with borohydride afforded the 5‐hydroxymethyl derivatives (VIII). The same 2,4‐dioxohexenoates (I) when treated with o‐phenylenediamine gave 2‐oxy‐quinoxalines (V; R = H, V; R = Me, V; R = Ph). The uv spectra data of these compounds are given