Synthesis of some new 5-chloro-7-mercapto-1-methyl/phenyl-1,2,4-triazolo[4,5-b]pyrazin-2(1H)-ones and 5-chloro-3-thiopyrazin-2(1H)-one derivatives as possible antibacterial and antifungal agents

Several new 5-chloro-7-mercapto-1-methyl/phenyl-1,2,4-triazolo[4,5-6]pyrazin-2(1/H)-ones V and their disul-phides VI, 5-chloro-3-mercapto-2(1H)-pyrazinonones III, 5-chloro-3-(N-aryl-N-acetylthioureido)-1-methyl/-phenyl-2(1H)-pyrazinones VII, 5-chloro-1-methyl/phenyl-3-sulphonamido-2(1H)-pyrazinones X and chloro-2-methyl/phenyl-(3-methyl)-3-thio-2(1H)-pyrazinones XI were synthesized starting from 3,5-dichloro-1-methyl/phenylpyrazin-2(1H)-ones I. Fifteen of these compounds were screened for their antibacterial and antifungal activity against two bacteria B. subtilis and S. aureus, and two fungi A. niger and H. oryzae. A possible structure activity relationship is given.