The fused skeleton piperidine-pyrimidones have been a rich source of biologically active molecular entities and are related to a wide family of compounds with well-known pharmacological properties. 1-5 Among the different substitution patterns that are known, tetrahydropyrido [4, 3-d] pyrimidines are important because of their potential biological and pharmaceutical activities. The tetrahydropyridopyrimidine core is a key pharmacophore in ...