STUDIES ON 1,2-BIS(4-CHLORO-1-PHTHALAZINYL) ETHANE AND 1,2-BIS{[}4(3H)-1-PHTHALAZINYL] ETHANE

1,2-Bis {[}4(3H)oxo-1-phthalazinyl]ethane (1) reacts with a mixture of PCl5/POCl3 to give 1, 2-bis(4-chloro-1-phthalazinyl)ethane (2). Compound 2 on treatment with different amines (hydrazine hydrate, phenylhydrazine, methyl amine, ethyl amine, aniline and benzyl amine) yields the corresponding 1, 2-bis(4-substituted amino-1-phthalazinyl)ethane derivatives (3a-1). Compound 2 also reacts with amino acids (glycine, glutamic acid or beta-alanine) in pyridine to give the corresponding 1,2-bis(4-carboxy-alkylamino-1-phthalazinyl)ethane derivatives (3g-i). Compounds 3g and 3h on refluxing with a mixture of acetic acid and sodium acetate afford 1,2-bis\{3(2H) oxo-imidazolo{[}2, 1-a]phthalazin-6-yl\}ethane (4) and 1,2-bis-\{2H-4(3H)-oxopyrimido{[}2, 1-a]phthalazin-7-yl\}ethane (5), respectively. Further, 2 on treatment with sodium azide in the presence of DMF gives 1, 2-bis-(tetrazolo{[}5, 1-a] phthalazin-6-yl)ethane (6). Compound 2 also reacts with acetylhydrazine in boiling butanol yields 1,2-bis(3-methyl-s-triazolo{[}2,1-a]phthalazin-6-yl)ethane (7) which is also obtained by the reaction of 3a with ethyl orthoacetate. Reaction of 1 with piperidine, morpholine, phthalamide and naphthol under Mannich reaction conditions furnish 2-bis{[}3-substituted-4(3H)-oxo-1-phthalazinyl]ethanes (9a-d). Decomposition of Grignard complex obtained from the reaction of 1 with methylmagnesium iodide or phenylmagnesium bromide afford 1, 2-bis(3, 4-dihydro-4, 4-dimethyl/diphenyl-1-phthalazinyl)ethanes (10a,b). Some of the synthesized compounds such as 2, 3a and 7 show antimicrobial activity against gram + ve and gram -ve bacteria.