In the presence of chiral phosphoric acid, an enantioselective Friedel-Crafts reaction of 4,7-dihydroindoles with aromatic trifluoromethyl ketones and ethyl 4,4,4-trifluoroacetoacetate has been realized. A series of 2-substituted 4,7-dihydroindoles with a trifluoromethylated tertiary alcohol moiety were obtained in 45-95% yields with 60-93% ee. Furthermore, 2-functionalized indole derivatives could be produced through a one-pot process.
- Brønsted acids
- Friedel-Crafts reaction
- trifluoromethyl-substituted compounds