Synthesis of 6-(4-Methyl-1-piperazinyl)-7H-indeno[2,1-c]quinoline Derivatives as Potential 5-HT Receptor Ligands

Two synthetic pathways for the achievement of the title compounds are reported. The key intermediate, namely 3-carboxy-4-phenyl-2(1H)-quinolinone 9, was directly cyclized into the corresponding 6-chloro-7H-indeno[2,1-c]quinolin-7-one 10 or alternatively it was esterified, reduced to the alcohol, chlorinated and cyclized into the 6-chloro-7H-indeno[2,1-c]quinoline 8. Further reaction of the chloroindenoquinoline derivatives with N-methylpiperazine afforded the piperazinyl derivatives 4a-c.