Catalytic and Chemodivergent Synthesis of 1-Substituted 9<i>H</i>-Pyrrolo[1,2-<i>a</i>]indoles via Annulation of β-CF<sub>3</sub> Enones with 3-Substituted Indoles
Haritha Sindhe, Nehanaz Saiyed, Akshay Kamble, Malladi Mounika Reddy, Amardeep Singh, Satyasheel Sharma
Abstract
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 9H-pyrrolo[1,2-a]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 9H-pyrrolo[1,2-a]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.