Synthesis of novel ferrocenyl-containing pyrazolo[4,3-c]quinolines

Synthesis of novel ferrocenyl-substituted pyrazolo[4,3-c]quinolines via the Pictet–Spengler reaction is reported. Iminium intermediate formed by the condensation of pyrazole-based arylamine substrates with ferrocenecarboxaldehyde in acidic medium, undergoes 6-endo cyclization with sufficiently reactive aromatic moiety to form a pyrazolo[4,3-c]quinoline ring.