Synthesis of Dihydroisoquinoline and Dihydropyridine Derivatives via Asymmetric Dearomative Three-Component Reaction

We report the first asymmetric three-component nucleophilic addition/dearomative [4+2] cycloaddition/isomerization cascade of transient dipoles generated from N-heteroarenes and allenoates with methyleneindolinones in the presence of chiral N,N'-dioxide/metal complexes. This tandem reaction enabled rapid access to versatile chiral polycyclic N-heterocycles with good to excellent enantioselectivities under mild reaction conditions in spite of the strong background reaction, including 1,2-dihydroisoquinoline, 1,2-dihydropyridine derivatives, and others. Meanwhile, a series of control experiments were conducted to elucidate the reaction mechanism and the roles of additives. [GRAPHICS]