Enantioselective Synthesis of Pyrrole-Based Spiro- and Polycyclic Derivatives by Iridium-Catalyzed Asymmetric Allylic Dearomatization and Controllable Migration Reactions.

The first highly diastereo- and enantioselective synthesis of five-membered spiro-2 H-pyrroles was achieved using an Ir-catalyzed asymmetric allylic dearomatization reaction. The spiro-2 H-pyrrole derivatives readily undergo a controllable and stereospecific allylic migration under acid catalysis, providing polycyclic pyrrole derivatives in excellent yields and ee values. Additionally, the novel Ir-complex K1, derived from [Ir(cod)Cl]₂ (cod=1,5-cyclooctadiene) and N-benzhydryl- N-phenyldinaphthophosphoramidite (BHPphos), showed excellent control of both diastereo- and enantioselectivities. [ABSTRACT FROM AUTHOR]