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Three-Component Synthesis of 2,3,5-Triaryl Pyridines
J. Barluenga*, A. Jiménez-Aquino, M. A. Fernández, F. Aznar, C. Valdés
Universidad de Oviedo, Spain
19 March 2008 (online)
A palladium-catalyzed, three-component synthesis of 2,3,5-triaryl-substituted pyridines is reported. The reaction system was devised incrementally and hence a good understanding of the individual steps has resulted. The first step, Pd-catalyzed coupling of alkenylbromide with morpholine, yields an activated alkene. Palladium catalysis also induces the coupling of the alkenylbromide with the silylimine to form the 2-aza-1,3-butadiene. Lewis acid catalysis with Yb(OTf)3 then facilitates a Diels-Alder reaction which, after elimination of morpholine and oxidation, yields the pyridine derivative.