Fe(OTf)3-catalyzed annulation of α,β-unsaturated ketoxime acetates with enaminones for the synthesis of functionalized 2,4-diarylpyridines

Abstract

Herein, we present a novel method for the synthesis of highly functionalized 2,4-diarylpyridines. This method involves a one-pot cascade reaction utilizing α,β-unsaturated ketoxime acetates and enaminones as substrates, encompassing a SET, Michael reaction, oxidation of allyl group carbon, and loss of one proton and one PhNH₂. The reaction occurred by refluxing a mixture of the starting materials in toluene with the catalyst Fe(OTf)₃, leading to the formation and cleavage of two bonds. The cascade reaction generates a series of functionalized pyridines. Notably, this method enables the synthesis of functionalized asymmetrical 2,4-diarylpyridines and offers an efficient alternative to the tedious multi-step syntheses traditionally employed. This approach is suitable for the combinatorial and parallel syntheses of pyridine derivatives in a one-pot reaction.