Hydrazine derivatives and o-benzoylbenzoic acid as a source of phthalazines with their antimicrobial activities

Starting from 2-benzoylbenzoic acid (1) and prototype hydrazine itself or some of its simple congeners produce phthalazin-1(2H)-one derivatives 2a-d. Reactions of 2 with P(2)S(5) or POCl(3) gave their thione derivatives 3a-c or the chloro derivative 4 respectively. Further reactions of phthalazines 3 and 4 with hydrazine derivatives afforded their hydrazinyl derivatives 5a-d. Compounds 5a and 5d were used as a precursor to triazolo 6 and pyrazolyl phthalazines 7. The antimicrobial activities of some of the prepared phthalazines were tested.