A facile regiocontrol in the palladium-catalyzed annulation of fluorine-containing internal alkynes with variously substituted 2-iodoanilines: A new regioselective synthesis of 2-or 3-fluoroalkylated indole derivatives

Treatment of various types of fluoroalkylated alkynes with o-iodoaniline in the presence of Pd(PPh(3))4 in DMF at 80 degreesC for 8 h mainly gave 2-fluoroalkylated indoles in high yields. The use of P(o-Tol)(3) instead of PPh(3) as a ligand led to the preferential formation of 3-fluoroalkylated indoles in high yields. Interestingly, the reaction of trifluoromethylated alkynes bearing a benzylic substituent afforded 2- or 3-trifluoroethylated indole derivatives in good yields.