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Modular Pyridine Synthesis from Oximes and Enals through Synergistic Copper/Iminium Catalysis

2013; American Chemical Society; Volume: 135; Issue: 10 Linguagem: Inglês

10.1021/ja312346s

1943-2984

Ye Wei, Naohiko Yoshikai,

Chemical Synthesis and Analysis

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.