Intramolecular Mizoroki–Heck Reaction in the Regioselective Synthesis of 4-Alkylidene-tetrahydroquinolines

The Mizoroki–Heck reaction of N-alkenyl-substituted 2-haloanilines is an effective protocol for the synthesis of substituted 4-alkylidene-tetrahydroquinoline derivatives, avoiding isomerization and oxidation. When non-substituted alkenes are used, the regioselectivity of the reaction can be directed towards the formation of an exocyclic or endocyclic double bond by choosing an adequate catalytic system. When the double bond is substituted by an amide moiety, the exocyclic double bond of E geometry is obtained selectively. Thus, this protocol efficiently synthesizes a series of 2-substituted tetrahydroquinolines with an exo α,β-unsaturated amide moiety at the C-4 position.