Nitrogen bridgehead compounds. Part 92.* Synthesis of 4-oxo-4H-pyrido[1,2-a]pyriniidine-3-carboxamides, -3-acetamides and their tetrahydro derivatives

István Hermecz, Lelle Vasvári-Debreczy, Ágnes Horváth, Judit Sipos, Mária Balogh, Benjámin Podányi, Katalin Kovács

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Abstract

N-Substituted 4-oxo-4H-pyrido[1,2-a]pyrimidine-3-carboxamides (6-45), -3-acetamides (59-61) and 1,6-dimethyl-4-oxo-1,6,7,8-tetrahydro-4H-pyrido[1,2-a]pyrimidine-3-carhoxamides (63-73) were synthesized in the reaction of amines and mixed anhydrides, prepared from 4-oxo-4H-pyrido[1,2-a]-pyrimidine-3-carboxylic acids (4), -3-acetic acids (58) and 1,6-dimethyl-4-oxo-1,6,7,8-tetrahydropyrido-[1,2-a]pyrimidine-3-carhoxylic acid (62) with methyl or ethyl chloroformate in the presence of triethylamine. Whereas the reaction of 6-methyl-4-oxo-6,7,8,9-tetrahydro-4H-pyrido[1,2-a]pyrimidine-3-acetic acid (53) with 2-phenylethylamines in boilings xylene gave the appropriate N-substituted 3-acetamides (54) and (55), reaction of 6-methyl-4-oxo-4H-pyrido[1,2-a]pyrimidine-3-acetic acid (56) with 2-phenylethylamine afforded a pyrrolidin-5-one derivative (57). 3-Acetic hydrazides (47, 48) and (50) were prepared from ethyl 4-oxo-4H-pyrido[1,2-a]pyrimidine-3-acetates (46) and the 6,7,8,9-tetrahydro derivative (49) with hydrazine hydrate. Both 4-oxo-4H-pyrido[1,2-a]pyrimidine-3-acetic hydrazide (47) and 6,7,8,9-tetrahydro-3-acetic hydrazide (50) were converted to 6,7,8,9-tetrahydro-3-acetamides (51, 52) by refluxing them in ethanol over Raney Ni.

Original languageEnglish
Pages (from-to)515-528
Number of pages14
JournalACH - Models in Chemistry
Volume135
Issue number4
Publication statusPublished - Dec 1 1998

ASJC Scopus subject areas

  • Chemistry(all)

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