Abstract
Synthesis of pyrimidine derivatives bearing the aryl azo group and evaluation of their antimicrobial activities was achieved using Thiouracil (1) as a starting material. The starting compound was methylated with CH3I to afford 5-methylthiouracil (2) which in turn was diazotized at position 5 via the reaction with diazonium salt of p-aminoacetophenone giving the azo compound (3). This compound was monobrominated to afford the bromo derivative (4) which was used for the preparation of thiazole derivatives (5a-c) by its reaction with substituted thiosemicarbazones. Also, it was reacted with some aldehydes yielding chalcones (7a-c). The methyl ketone (3) was also reacted with thiosemicarbazides giving thiosemicarbazone derivatives (8a-c). On the other hand, reacting (3) with semicarbazide afforded the corresponding semicarbazone (9) which in turn was reacted with SeO or SOCl2 yielding selene diazole or Thiadiazole (10) & (11) respectively. In addition, the methyl ketone (3) was a good substrate for the preparation of pyridines (12a-c) by its reaction with some aldehydes in presence of ethyl acetoacetate and excess ammonium acetate. Finally, Mannich reaction was carried out by reacting the key intermediate (3) with some secondary amines, paraformaldehyde to afford Mannich's bases (13a-c). The prepared compounds showed variable activities as antimicrobial agents and indicated that substitution of 2-thiouracil at the 5th position retained the antimicrobial activity.