Synthesis of 2-Alkenyl-Tethered Anilines

Three general routes for the synthesis of (E)-2-alkenyl-tethered anilines have been developed. The first route involves a 3-aza-Cope rearrangement of N-allylic anilines in the presence of a Lewis acid. The requisite N-allylic anilines were prepared by the addition of vinylmagnesium reagents to the corresponding aldimines. The second route details a direct cross-metathesis of 2-allylic or 2-homoallylic anilines with styrenes. The third route involves a palladium-catalyzed C–N cross-coupling of aryl halides. Taken together, these three strategies allowed access to the requisite aniline substrates with pendant alkenes at the 2-position with excellent trans selectivities.