Synthesis and Reactions of 6-Amino-4-aryl-2H-1,3,5-thiadiazine-2-thiones

Koji TAKIZAWA, Takayuki SUYAMA*, Jun-ichi YAMAGUCHI and Susumu MIKKAICHI

Department of Applied Chemistry, Faculty of Engineering, Kanagawa Institute of Technology; Shimo-ogino, Atsugi-shi 243-0292 Japan
Department of Chemistry, School of Medicine, Kyorin University; Shinkawa, Mitaka-shi 181-8611 Japan

6-Amino-4-aryl-2H-1,3,5-thiadiazine-2-thiones 6 were obtained by the reaction of N-cyanobenzamidines 5 with carbon disulfide in the presence of potassium hydroxide at |5 °C via N-(N-cyanobenzimidoyl)imidodithiocarbonate. Whereas alkali degradation of aliphatic amidines such as N-cyanoformamidine or N-cyanoacetamidine gave no desired compounds under similar conditions. Treatment of 6 with alkali or acid produced 1,3,5-triazines or N-benzoylthiourea derivatives, respectively. The reaction of 6 with primary or secondary amines in DMF smoothly proceeded to give N1-substituted N2-thiocarbamoylbenzamidines 19. Considering the structures of products given by reactions of 6 with some nucleophiles, it was found that an amidino part of 6 was the most reactive site and nucleophiles attacked at 4-position of 1,3,5-thiadiazine ring. Treatment of 6 with methyl iodide in the presence of base gave 2,4-bis(methylthio)-1,3,5-triazines 21 at |5 °C.

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