Abstract
A series of pyridines, pyrimidinones, oxazinones and their derivatives were synthesized as antimicrobial agents using citrazinic acid (2,6-dihydroxyisonicotinic acid) as a starting material. α,β-Unsaturated ketones
3a
–
c
were condensed with cyanothio-acetamide in the presence of ammonium acetate to give 2-cyanopyridinethiones
4a
–
c
, which were reacted with ethyl chloroacetate to yield the corresponding cyano esters
5a
–
c
. The esters
5a
–
c
were cyclized by action of sodium methoxide to aminoesters
6a
–
c
, which were aminolyzed with ammonia to corresponding aminoamide derivatives
7a-c
. Also, the esters
6a
–
c
were hydrolyzed with NaOH to the corresponding sodium salt
8a
–
c
, which were treated with acetic anhydride to afford 2-methyloxazinones
9a
–
c
. The latter compounds were treated with ammonium acetate to afford 2-methylpyrimidinones
10a
–
c
, followed by methylation with methyl iodide to yield 2,3-dimethyl-pyrimidinones
11a
–
c
. The antimicrobial screening showed that many of these compounds have good antibacterial and antifungal activities comparable to streptomycin and fusidic acid used as reference drugs.