Regioselective synthesis of asymmetrically substituted 2-quinoxalinol salen ligands.

Diamino-2-quinoxalinols are reacted with salicylaldehyde derivatives to produce 2-quinoxalinol imines regioselectively as one isomer in good yield. Regioselectivity has been determined through the use of isotopic 15N labeling experiments. The 2-quinoxalinol imines may then be reacted without further purification with additional salicylaldehyde derivatives to yield asymmetrically substituted 2-quinoxalinol salens.