INTRAMOLECULARLY HYDROGEN-BONDED 3-PHENACYL-1H-PYRIDO[3,4-B]-PYRAZIN-2-ONE AND 2-PHENACYL-4H-PYRIDO[3,4-B]PYRAZIN-3-ONE

Twelve phenacyl derivatives of 1H-pyrido[3,4-b]pyrazin-2-ones and 4H-pyrido[3,4-b]pyrazin-3-ones have been synthesized. In these compounds, C = N double bonds at the 3 and 4 positions in the former compounds and those at the 1 and 2 positions in the latter compounds migrate onto the side chains to form phenacylidene structures. These migrations are facilitated by chelation between side chain carbonyl and the proton attached to the ring nitrogen atom which was generated by the migration. All the hydrogen-bonded structures appear to be stable as shown by their ir spectra in the crystalline state, and by their H-1 nmr spectra in solution.