Palladium-catalyzed direct C-2 arylation of indoles with potassium aryltrifluoroborate salts.

Mild conditions have been developed to achieve Pd(OAc)2-catalyzed regioselective cross-coupling between indoles and potassium aryltrifluoroarylborates in the presence of Cu(OAc)2 in acetic acid at room temperature. A variety of potassium aryltrifluoroborates selectively undergo the direct arylation across indoles and afford 2-aryl indoles in moderate to good yields.