A reusable zirconium(IV) Schiff base complex catalyzes highly efficient synthesis of quinoxalines under mild conditions

A zirconium(IV) complex of a bidentate Schiff base (ZrL₂Cl₂) has been synthesized by the reaction of (z)-N-benzylidene-2-hydroxypropane-1-amine (HL) and ZrCl₄. Spectroscopic data and elemental analyses are consistent with a monomeric complex with a ligand:Zr ratio of 2:1. The catalytic activity of ZrL₂Cl₂ has been investigated for the efficient synthesis of a wide variety of quinoxaline derivatives under mild conditions. The employment of ethanol as an environmentally benign solvent in this high yield method, along with high turnover numbers and reusability of the catalyst providing ready scalability, makes it appropriate for practical applications.