Anti-inflammatory activity of heterocyclic systems using abietic acid as starting material

A series of pyridines, pyrimidinone, oxazinones, and their derivatives were synthesized as anti-inflammatory agents using abietic acid (7-isopropyl-1,4a-dimethyl-1,2,3,4,4a,4b,5,6,10,10a-decahydrophenanthrene-1-carboxylic acid) as the starting material. The arylidiene derivative was treated with cyanothioacetamide to give cyano pyridine-thione, which was reacted with ethyl chloroacetate to yield the corresponding cyano ester. The ester was hydrolysed to the sodium salt, which was reacted with acetic anhydride to afford 2-methyloxazinone, which was treated with ammonium acetate to afford 2-methylpyrimidinone followed by methylation with methyl iodide to yield 2,3-dimethyl- pyrimidinone. In addition, the oxazinone derivative was reacted with aniline or hydrazine hydrate to give 3-phenyl- or 3-aminopyrimidinones. The latter reacted with thiophene-2-carboxaldehyde or phenylisothiocyanate to afford Schiff's bases or thiosemicarbazide derivatives. The pharmacological screening showed that many of these compounds have good anti-inflammatory activity comparable to Prednisolone (R) as reference drug.