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.
|Number of pages||14|
|Journal||ACH - Models in Chemistry|
|Publication status||Published - Dec 1 1998|
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