Exploiting the Multidentate Nature of Chiral Disulfonimides in a Multicomponent Reaction for the Asymmetric Synthesis of Pyrrolo[1,2-a]indoles: A Remarkable Case of Enantioinversion

A new multicomponent coupling reaction for the enantioselective synthesis of pyrrolo[1,2‐a]indoles under the catalysis of a chiral disulfonimide is described. The high specificity of the reaction is a consequence of the multidentate character of the Brønsted acid catalyst. Insights from DFT calculations helped explain the unexpected high enantioselectivity observed with the simplest 3,3′‐unsubstituted binaphthyl catalyst as a result of transition‐state stabilization by a network of cooperative noncovalent interactions. The remarkable enantioinversion resulting from the simple introduction of substituents at 3‐ and 3′‐positions, the first reported example of this phenomenon in the context of binaphthalene‐derived Brønsted acid catalysis, was instead attributed to destabilizing steric interactions. Leicht geschaltet: Im Zusammenhang mit einer neuen, hoch selektiven Synthese von Pyrrolo[1,2‐a]indolen werden einige außergewöhnliche Merkmale chiraler Disulfonimid‐Organokatalysatoren demonstriert. Ein Drei‐Punkt‐Koordinationsmodell erklärt die hohe Enantioselektivität. Aus einer einfachen Strukturmodifikation des Katalysators resultiert eine ungewöhnliche Umschaltung der Enantioselektivität (siehe Schema).