A New Approach to Di- and Tetrasubstituted 2,3-Dihydropyridin-4(lH)-ones through Aza-Diels-Alder Reaction Promoted by Silicon Tetrachloride

摘要

Silicon tetrachloride promotes an aza-Diels-Alder reaction with a range of imines and Danishefsky's diene or an alkylated derivative, giving the desired products in good to excellent yields.The aza-Diels-Alder reaction is a powerful method for the construction of six-membered nitrogen heterocycles.1'2 Recent advances have been made in a number of Lewis acid catalyzed aza-Diels-Alder reactions in organic solvents,3 aqueous media,4 and ionic liquids.5 Moreover, the use of Bransted acid6 and hydrogen-bond catalysis7 provides an alternative to the use of metal catalysts. Asymmetric versions of this transformation have also been reported with several chiral metal complexes8-9 or chiral Brensted acid catalysts.