64077-00-5Relevant academic research and scientific papers
Nitrogen bridgehead compounds. Part 92.* Synthesis of 4-oxo-4H-pyrido[1,2-a]pyriniidine-3-carboxamides, -3-acetamides and their tetrahydro derivatives
Hermecz, Istvan,Vasvari-Debreczy, Lelle,Horvath, Agnes,Sipos, Judit,Balogh, Maria,Podanyi, Benjamin,Kovacs, Katalin
, p. 515 - 528 (2007/10/03)
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.
