Synthesis and biological evaluation of some N-ethoxyphthalimido-4-phenyl-6- subsitutedphenyl-2,3a,4,5-tetrahydro-3H-indazol-3-one via Robinson annulations reaction

Compounds 4-[4-substitutedphenyl]-6-phenyl-2,3a,4,5-tetrahydro-3H-indazol-3-one (3a-d) were synthesized via robinson annulation. Robinson annulation is michael addition reaction followed by aldol condentation. ? B unsaturated carbonyl compounds (1a-d) were cyclized with ethylacetoacetate produced ethyl 6-[4-substitutedphenyl]-2-oxo-4-phenyl cyclohex-3-ene-1-carboxylate (2a-d). Compounds (2a-d) were refluxed with hydrazine hydrate in the presence of acetic acid yielded 4-[4-substitutedphenyl]-6-phenyl-2,3a,4,5-tetrahydro-3H-indazol-3-one (3a-d). In the final step compounds (3a-d) were treated with bromoethoxyphthalimide gave final products N-ethoxyphthalimido-4-[4-substituted phenyl]-6-phenyl-2,3a,4,5-tetrahydro-3H-indazol-3-one (5a-d). In another route pyrazolo benzodiazepine compounds containing alkoxyphthalimide moiety have been synthesized through a multiple steps pathway starting from substituted chalcones (la-c). Cyclisation of these with hydrazine hydrate in acetic acid afforded 1-[5-(4-substitutedphenyl)-3-phenyl-4,5-dihydro-1H-pyrazol-1-yl]ethanone (6a-c). Base catalyzed condensation of (6a-c) with benzaldehyde yielded 1-[{5-(4-substitutedphenyl-3-phenyl)-3-phenyl-4,5-dihydro-1H-pyrazol -1-yl]ethanone (7a-c). These compounds treated with o-phenylenediamine gave compounds (8a-c). These (8a-c) refluxed with bromoethoxyphthalimide afforded final compounds N-ethoxyphthalimido-2-(phenyl)-4-[5-(4-substitutedphenyl)-3-phenyl-4,5-dihydropyrazol-1-yl]-1H-benzo(b)[1,5] diazepine (9a-c). In the another route compounds (2a-d) cyclised with hydroxylamine and furnish (10a-d). The structures of all the synthesized compounds were supported by spectral and analytical studies.