Nitrogen bridgehead compounds. IX. Synthesis and reactions of 2,3-disubstituted pyrido[1,2-α]pyrimidin-4-ones (1)

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Abstract

A series of 4H-pyrido[1,2-α]pyrimidin-4-ones was prepared by the cyclization of substituted 2-aminopyridines with βketocarboxylic esters in polyphosphoric acid or in mixtures of the latter with phosphoryl chloride. Catalytic hydrogenation (over palladium on charcoal or Raney nickel) of the products afforded the corresponding 6,7,8,9-tetrahydropyridopyrimidinones. Thermal treatment of the 6-substituted derivatives gave 1,8-naphthyridin-4-ones in high yields. Oxo to thio exchange was successful only with substrates unsubstituted at C-6.

Original languageEnglish
Pages (from-to)457-460
Number of pages4
JournalJournal of Heterocyclic Chemistry
Volume16
Issue number3
DOIs
Publication statusPublished - Apr 1979

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Nitrogen Compounds
Charcoal
Cyclization
Palladium
Nickel
Hydrogenation
Esters
Heat treatment
Derivatives
Substrates
phosphoryl chloride
alpha-aminopyridine
polyphosphoric acid

ASJC Scopus subject areas

  • Organic Chemistry

Cite this

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title = "Nitrogen bridgehead compounds. IX. Synthesis and reactions of 2,3-disubstituted pyrido[1,2-α]pyrimidin-4-ones (1)",
abstract = "A series of 4H-pyrido[1,2-α]pyrimidin-4-ones was prepared by the cyclization of substituted 2-aminopyridines with βketocarboxylic esters in polyphosphoric acid or in mixtures of the latter with phosphoryl chloride. Catalytic hydrogenation (over palladium on charcoal or Raney nickel) of the products afforded the corresponding 6,7,8,9-tetrahydropyridopyrimidinones. Thermal treatment of the 6-substituted derivatives gave 1,8-naphthyridin-4-ones in high yields. Oxo to thio exchange was successful only with substrates unsubstituted at C-6.",
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T1 - Nitrogen bridgehead compounds. IX. Synthesis and reactions of 2,3-disubstituted pyrido[1,2-α]pyrimidin-4-ones (1)

AU - Fülöp, F.

AU - Hermecz, I.

AU - Mészáros, Z.

AU - Dombi, G.

AU - Bernáth, G.

PY - 1979/4

Y1 - 1979/4

N2 - A series of 4H-pyrido[1,2-α]pyrimidin-4-ones was prepared by the cyclization of substituted 2-aminopyridines with βketocarboxylic esters in polyphosphoric acid or in mixtures of the latter with phosphoryl chloride. Catalytic hydrogenation (over palladium on charcoal or Raney nickel) of the products afforded the corresponding 6,7,8,9-tetrahydropyridopyrimidinones. Thermal treatment of the 6-substituted derivatives gave 1,8-naphthyridin-4-ones in high yields. Oxo to thio exchange was successful only with substrates unsubstituted at C-6.

AB - A series of 4H-pyrido[1,2-α]pyrimidin-4-ones was prepared by the cyclization of substituted 2-aminopyridines with βketocarboxylic esters in polyphosphoric acid or in mixtures of the latter with phosphoryl chloride. Catalytic hydrogenation (over palladium on charcoal or Raney nickel) of the products afforded the corresponding 6,7,8,9-tetrahydropyridopyrimidinones. Thermal treatment of the 6-substituted derivatives gave 1,8-naphthyridin-4-ones in high yields. Oxo to thio exchange was successful only with substrates unsubstituted at C-6.

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