Enhanced catalytic activity of Zr(IV) complex with simple tetradentate Schiff base ligand in the clean synthesis of indole derivatives

Zirconium (IV) tetradentate Schiff base (salphen) complex has been successfully used for efficient synthesis of wide variety of indole derivatives in EtOH as a standard green solvent under mild conditions. The investigation of turnover number and reusability of the catalyst indicate well the high efficiency and relative stability of the Zr-complex in this reaction.