title: Modular pyridine synthesis from oximes and enals through synergistic copper/iminium catalysis.
abstract: We describe here a [3+3]-type condensation reaction of O-acetyl ketoximes and α,β-unsaturated aldehydes that is synergistically catalyzed by a copper(I) salt and a secondary ammonium salt (or amine). This redox-neutral reaction allows modular synthesis of a variety of substituted pyridines under mild conditions with tolerance of a broad range of functional groups. The reaction is driven by a merger of iminium catalysis and redox activity of the copper catalyst, which would initially reduce the oxime N-O bond to generate a nucleophilic copper(II) enamide and later oxidize a dihydropyridine intermediate to the pyridine product.
authors: Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.
authors: Ye
authors: Y
authors: Wei
authors: Naohiko
authors: N
authors: Yoshikai
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D000588:Amines / Q000737:chemistry*; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D015394:Molecular Structure; D010091:Oximes / Q000737:chemistry*; D011725:Pyridines / Q000138:chemical synthesis* / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*
chemical_list: D000447:Aldehydes; D000588:Amines; D010091:Oximes; D011725:Pyridines; D000644:Quaternary Ammonium Compounds; D003300:Copper; C023666:pyridine