Catalytic and Chemodivergent Synthesis of 1-Substituted 9-Pyrrolo[1,2-]indoles via Annulation of β-CF Enones with 3-Substituted Indoles.

Chemodivergent reactions are more advantageous in organic synthesis that yield diversely functionalized scaffolds from common starting materials. Herein, we report an efficient metal-free chemodivergent protocol for the synthesis of 1-substituted 9-pyrrolo[1,2-]indole derivatives in the presence of catalytic amounts of Lewis acid/Brønsted acid conditions using 3-substituted indoles and β-trifluoromethyl-α,β-unsaturated ketones. Fine-tuning of the catalyst and solvent system in the reaction conditions deliver the trifluoromethyl, trifluoroethylcarboxylate, or carboxylic acid substituents on the C1-position of 9-pyrrolo[1,2-]indole derivatives in situ. It is postulated that the solvent and LA/BA catalyst interaction was found to be crucial for the catalytic C-F activation in these transformations.