Synthesis and reactions of some new 2,3-dihydro-5<i>H</i>-5,7-diarylthiazolo[3,2-<i>a</i>] pyrimidine-3-one derivatives and their antibacterial and fungicidal activity

Abstract

Arylmethylene acetophenone derivatives (chalcones) <b>la-d</b> react with thiourea in glacial acetic acid CH₃COOH/Ac₂O<i> </i>in the presence of anhydrous sodium acetate to yield 1,4-dihydro-4,6-diarylpyrimidine-2-thione <b>2a-d</b> which on treatment with chloroacetic acid furnish 2,3 dihydro-5<i>H</i>-5,7-diaryl thiazolo[3,2-<i>a</i>] pyrimidine-3-one derivatives <b>3a-d</b>. Compounds <b>3a-d</b> on condensation with aromatic aldehydes yield 2(arylmethylene )-2,3-dihydro-5<i>H</i>-5,7 -diaryl-thiazolo[3,2-<i>a</i>]pyrimidine-3-one derivatives <b>4a-f</b>. Also compounds <b>4a-d</b> have been prepared directly from <b>2a,b</b> by the reaction with chloroacetic acid and the aromatic aldehyde. Coupling of <b>3a-d</b> with aryl diazonium salts in pyridine yields 2-(aryl hydrazo)-2,3-dihydro-5,7-diaryl-

5H-thiazolo[3,2-<i>a</i>]pyrimidine-3-ones <b>5a-f</b>. Compounds <b>2a-d</b> on reaction with 2-bromopropionic or 3-bromopropionic acid give 2,3-dihydro-2-methyl-5<i>H</i>-5,7-diaryl-thiazolc[3,2-<i>a</i>]pyrimidine-3-one <b>6a-d</b> and 2,3-dihydro-6<i>H</i>-6,8-diaryl-pyrimido[3,2-<i>b</i>]-1,3- thiazin-4-ones <b>7a-d</b> respectively. A number of 3,4-dihydro-4,6-diaryl pyrimidine-2yl-thio)acetahydrazide <b>8a-c</b>,2-(3,4-dihydro-4,6-diaryl-pyrimidine-2yl-thio)acetanilide derivatives <b>8d-g</b>, 2-(3,4-dihydro-4,6-diaryl-pyrimidine-2yl-thio)propionylhydrazide <b>9a-c</b>, 2-(3,4-dihydro-4,6-diaryl-pyrimidine-2yl-thio)propionylanilide <b>9d-f</b> and 3-(3,4-dihydro-4,6-diaryl- pyrimidine-2yl-thio)propionamide <b>10a-e</b> derivatives are readily obtained in good yield by the action of the corresponding amines on compounds 3,6 or 7 successively. The anilide <b>8d</b> also has been obtained by the reaction of compound <b>2a</b> with chloroacetanilide.