Synthesis of a new series of heterocyclic scaffolds for medicinal purposes.

A new series of substituted 8-fluro-4H-pyrimido[2,1-b] [1,3]benzothiazole-4-ones () substituted 7-methyl-4H-isoxazolo[2,3-a]pyrimidin-4-ones, and substituted 2-methyl-5,6,7,8-tetrahydro-9H-isoxazolo[2,3-a]pyridopyrimidin-9-ones, compounds I-VII, have been prepared via condensation of beta-keto esters with 2-aminopyridine derivatives, in the presence of polyphosphoric acid. The same technique has also been used to prepare diazepine compounds, VIII-X, by condensation of a gamma-keto ester with 2-aminopyridine derivatives. Details of synthetic procedures are shown. The new compounds have been characterized by elemental analysis, GC-MS, FT-IR and NMR spectrometry. Antibacterial, antifungal and anticancer (cytotoxic) activities, for three of these compounds, have been investigated and are presented.