title: Complexes of Schiff bases and intermediates in the copper-catalyzed oxidative heterocyclization by atmospheric oxygen.
abstract: After complexation with copper(II) ions, Schiff bases 1a-d may undergo an oxidative ring closure using atmospheric oxygen to give a number of imidazo[1,5-a]pyridines 2, an imidazo[1,5-a]imidazole 3, and an imidazo[5,1-a]isochinoline 4. This ligand oxidation can be performed with catalytic amounts of copper ions in the reaction. A catalytic cycle for the copper-catalyzed oxidative heterocyclization will be presented together with isolated copper complexes of Schiff bases 1a,b and intermediates 5 and 8 that were found by X-ray structure analyses which confirm this reaction scheme.
authors.affiliation: Institute for Technical Chemistry (ITC-CPV), Forschungszentrum Karlsruhe, P.O. Box 3640, 76021 Karlsruhe, Germany.
authors.forename: Martin E
authors.initials: ME
authors.lastname: Bluhm
authors.forename: Michael
authors.initials: M
authors.lastname: Ciesielski
authors.forename: Helmar
authors.initials: H
authors.lastname: Görls
authors.forename: Olaf
authors.initials: O
authors.lastname: Walter
authors.forename: Manfred
authors.initials: M
authors.lastname: Döring
mesh_terms: D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D003500:Cyclization; D007093:Imidazoles / Q000138:chemical synthesis*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D011725:Pyridines / Q000138:chemical synthesis*; D012545:Schiff Bases / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D007093:Imidazoles; D011725:Pyridines; D012545:Schiff Bases; D003300:Copper; D010100:Oxygen