Synthesis, anti-inflammatory, analgesic and anticonvulsant activities of 1,8-dihydro-1-aryl-8-alkyl pyrazolo(3,4-b)indoles

A series of 1,8-dihydro-1-aryl-8-alkyl pyrazolo(3,4-b)indoles 4a-j, 5a-j and 6a-j has been synthesized and tested for their anti-inflammatory and anticonvulsant activities. Formation of the pyrazoloindole derivatives was achieved by treating arylhydrazones of N-alkyl indole-3-carboxaldehydes 1a-j, 2a-j and 3a-j with ten times their mass of polyphosphoric acid as a condensing agent. The newly synthesized compounds were evaluated for their anti-inflammatory, analgesic and anticonvulsant activities compared to indomethacin, flufenamic acid and diazepam as positive controls. Detailed synthesis, spectroscopic and toxicity data are reported.