T. Seki et Y. Iwanami, INTRAMOLECULARLY HYDROGEN-BONDED 3-PHENACYL-1H-PYRIDO[3,4-B]-PYRAZIN-2-ONE AND 2-PHENACYL-4H-PYRIDO[3,4-B]PYRAZIN-3-ONE, Journal of heterocyclic chemistry, 31(4), 1994, pp. 1065-1067
Twelve phenacyl derivatives of 1H-pyrido[3,4-b]pyrazin-2-ones and 4H-p
yrido[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 an
d 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 a
ttached to the ring nitrogen atom which was generated by the migration
. All the hydrogen-bonded structures appear to be stable as shown by t
heir ir spectra in the crystalline state, and by their H-1 nmr spectra
in solution.