Synthesis and Antimicrobial Activities of Some 6-Methyl-3-Thioxo-2,3-Dihydro-1,2,4-Triazine Derivatives

<div><p></p><p>4-Arylidene-imidazole derivatives (<b>4a</b>,<b>b</b>) were readily prepared by reacting 4-am- ino-6-methyl-3–thioxo-2,3–dihydro[1,2,4]triazin-5(4H)-one (<b>1</b>) with 4-arylidene-2-phenyl- 4H-oxazol-5-one (<b>2</b>). Reaction of <b>1</b> with some aromatic aldehydes in presence of triethylphosphite exclusively afforded the corresponding aminophosphonates <b>5a</b>-<b>c</b>. Reaction of <b>1</b> with 3-phenyl-1H-quinazoline-2,4-dione (<b>6a</b>) and/or 3-phenyl-2-thioxo-2,3-dihydro- 1H-quinazolin-4-one (<b>6b</b>) gave 2-(6-methyl-5-oxo-3-thioxo-2,5-dihydro-3H-[1,2,4]triazin-4-ylimino)-3-phenyl-2,3-dihydro-1H-quinazolin-4-one (<b>7</b>). Moreover, on treating <b>1</b> with 2-phenylbenzo[d][1,3]thiazine-4-thione (<b>8</b>), 6-methyl-4-(2-phenyl-4-thioxo-4H-quinazolin-3-yl)-3-thioxo-3,4-dihydro-2H-[1,2,4]triazine-5-one (<b>9</b>) was obtained in 65% yield. Reaction of <b>1</b> with 4-sulfonylaminoacetic acid derivatives (<b>10a</b>,<b>b</b>) afforded the corresponding sulfonamides (<b>11a</b>,<b>b</b>), respectively. Acid hydrolysis of <b>11a</b> afforded 7-aminomethyl-3-methyl[1,3,4]thiadiazole[2,3-c][1,2,4]triazin-4-one (<b>12</b>). 4-Amino-6-methyl-3-(morpholine-4-ylsulfanyl)-4H-[1,2,4]triazin-5-one (<b>14</b>) was prepared by reacting compound <b>1</b> with morpholine in presence of KI/I₂, while 3,3′-bis(4-amino-6-methyl-5-oxo-triazinyl)disulfide (<b>16</b>) was obtained by oxidation of <b>1</b> with lead tetraacetate. The antimicrobial activity of the products was evaluated against Gram-positive and Gram-negative bacteria as well as the fungus Candida albicans.</p> <p>[Supplementary materials are available for this article. Go to the publisher's online edition of <i>Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental files: Additional text, figures, and tables.</i>]</p>