Synthesis of some N,N-diethoxyphthalimido-5-(substitutedphenyl)-3-methyl-1,3<i style="">a</i>,4,5-tetrahydropyrazolo[3,4-<i>c</i>] pyrazole-4-spiro-5-substituted-1<i>H</i>-indole-2-one

885-8895-Methyl-2,4-dihydro-3H-pyrazol-3-one reacts with isatin 1a,b in ethanol to give a solid product. On addition of warm benzene, one part (benzene soluble) is 4a,b and another part (benzene insoluble) is 2a,b. Compounds 3,5-dimethyl-4,7-dihydro-1H-pyrazolo[4′,3′:5,6]pyrano[2,3c]pyrazole-4-spiro-5-substituted-1H-indole-2-one 2a,b on treatment with bromo­ethoxyphthalimide in DMF yield N,N,N-triethoxyphthalimido-3,5-dimethyl-4,7-dihy­dro-1H-pyrazolo [4′,3; 5,6]pyrano[2,3-c]pyrazole-4-spiro-5-sub­sti­tuted-1H-indole-2-one 3a,b. 3-(3-Methyl-5-oxo-1,5-dihydro-4H-pyrazol-4-ylidene)-1,3-dihydro-2H-indol-2-one 4a,b are converted to corresponding pyrazolopyrazole derivatives 5a-f by reaction with substituted phenylhydrazine. These are finally condensed with bromoethoxyphthalimide in DMF and pyridine as a base to give titled compounds N,N-diethoxyphthalimido-5-(substituted phenyl)-3-methyl-1,3a,4,5-tetrahydropyrazolo[3,4-c]pyrazole-4-spiro-5-substituted-1H-indole-2-one 6a-f. The structures of all the synthesized compounds are supported by spectral and analytical data