Simple Electrochemical Synthesis of Pyrazolo[4,3-c]quinoline Derivatives

Abstract

Valuable pyrazolo[4,3-c]quinoline derivatives were synthesized efficiently from the easily available 7-Chloro-4-hydrazinoquinoline through electrochemical synthesis under moderate and scalable electrolytic conditions afforded linear hydrazones (3a-g) then the cyclized one (4a-g). The conduct of the reactions was performed in a simple undivided cell under constant current without oxidizing reagents or transition metal catalysts. The synthesized products of the cyclization reaction have been characterized via UV/Vis spectrophotometry, 1H-NMR and FTIR spectroscopy, the understanding of the mechanism of the reaction, the importance of reactant structure to control the rate of the reaction and equilibria in the process is substantial. The applying of this protocol to the effective synthesis of key intermediates for antidiabetic compounds was done.