1H, 13C and 15N NMR spectral analysis of substituted 1,2,3,4-tetrahydro-pyrido[1,2-a]pyrimidines.

The NMR spectroscopic data of a series of thirty-four 3-acylpyrido[1,2-a]pyrimidinium salts are analyzed, which were prepared as either perchlorates or chlorides. Methyl group substituted 3-aroyltetrahydropyrido[1,2-a]pyrimidines with the methyl substituent in positions 6, 8 and 9 as well as both in positions 6 and 8 were investigated bearing various aroyl substituents. Unequivocal assignment of all resonances was achieved via two-dimensional (1)H,(1)H-COSY measurements, (1)H,(13)C and (1)H,(15)N HSQC as well as HMBC experiments, and important diagnostic CH and NH couplings in the heteroaromatic ring system are evaluated.

Synthesis and evaluation of pyrido[1,2-a]pyrimidines as inhibitors of nitric oxide synthases.

A series of new 3-aroylpyrido[1,2-a]pyrimidines were synthesized from aryl methyl ketones in a simple two-step procedure and evaluated as nitric oxide synthases (NOS) inhibitors. In order to perform a structure-activity relationship study, different aroyl groups were introduced in 3-position and methyl groups were introduced at different positions of the pyrimidine heterocycle. Compounds with a biphenyloyl, benzyloxybenzoyl or naphthoyl group displayed the highest inhibitory effects which were further increased by introduction of a methyl group in position 8 of the pyrido[1,2-a]pyrimidine moiety.