Rhodium-Catalyzed Intramolecular Acylation of 2-(Indol-1-yl)-benzoic Acids under Redox-Neutral Conditions

We developed a novel access to indoloindolone by a rhodium-catalyzed intramolecular acylation of 2-(indol-1-yl)benzoic acids. This reaction proceeds via the in situ formation of a mixed anhydride under redox-neutral reaction conditions. Preliminary mechanistic investigations revealed that the in situ formed mixed anhydride participates in the C-H activation step, which is facilitated by a RhI catalyst. The utility of this reaction was demonstrated by a large-scale reaction.

Automated summary

We have developed a novel approach to synthesize indoloindolone through a rhodium-catalyzed intramolecular acylation of 2-(indol-1-yl)benzoic acids. This reaction proceeds by the in situ formation of a mixed anhydride under redox-neutral reaction conditions. Preliminary mechanistic studies revealed that the in situ formed mixed anhydride participates in the C-H activation step facilitated by a RhI catalyst. The usefulness of this reaction was demonstrated through a large-scale reaction.