517895-69-1Relevant articles and documents
Synthesis of halogenated 4H-pyrido[1,2-a]pyrimidin-4-ones
Molnar, Annamaria,Faigl, Ferenc,Podanyi, Benjamin,Finta, Zoltan,Balazs, Laszlo,Hermecza, Istvan
experimental part, p. 2477 - 2488 (2010/04/29)
Halogenated 4H-pyrido[l,2-a]pyrimidin-4-one were synthesized by thermal cyclization and decarboxylation of isopropylidene (2-pyridylamino)methylenemalonates, prepared from 2-aminopyridines and isopropylidene methoxymethylenemalonate formed in situ. Instead of 4H-pyrido[l,2-a]pyrimidin-4-ones, the 6-chloro and 6-bromo derivatives afforded mixtures of 7-halo-l,4-dihydro-l,8-naphthyridin-4-ones and 1-(6-halo-2-pyridyl)-3-[(6-halo-2-pyridylamino)methylene]-1,2,3,4-tetrahydropyridine-2,4-diones. The latters formed from N-(2-pyridyl)iminoketenes, the common intermediates of 4H-pyrido[l,2-a]pyrimidin-4-one and l,8-naphthyridin-4-ones, via a "head-to-tail" [4+2] cycloaddition. 3-Halo-4H-pyrido[l,2-a]pyrimidin-4-ones were obtained from 4H-pyrido[1,2-a]pyrimidin-4-one with N-halosuccinimides. The structures of the new compounds were characterized by means of 1H NMR and 13C NMR examinations.
Exotic amino acids. 6. Synthesis of substituted 4-oxo-4H-pyrido[1,2-a]pyrimidines
Ravina,Zicane,Petrova,Gudriniece,Kalejs
, p. 836 - 839 (2007/10/03)
2-Pyridylaminomethyleneisopropylidenemalonates, prepared from ethoxymethyleneisopropylidenemalonate and 2-aminopyridines, form 4-oxo-4H-pyrido[1,2-a] pyrimidines at their melting points and are separated from the reaction mixture by sublimation.
