Synthesis of 3,4-dihydropyrrolo[2,1-a]isoquinolines based on [3+2] cycloaddition initiated by Rh2(cap)4-catalyzed oxidation

Azomethine ylides have been efficiently generated via Rh2(cap)4-catalyzed oxidation of tetrahydroisoquinoline derivatives in the presence of base. The ylides are trapped in situ via [3+2] cycloaddition with dipolarophiles and subjected to oxidative aromatization facilitated by N-bromosuccinimide to provide 3,4-dihydropyrrolo[2,1-a]isoquinoline derivatives in moderate to excellent yields.