Synthesis of aryl-substituted quinolines and tetrahydroquinolines through Suzuki-Miyaura coupling reactions

The synthesis and characterization of substituted (trifluoromethoxy, thiomethyl, and methoxy) phenyl quinolines is described. Dichlorobis(triphenylphosphine)palladiunn(II)-catalyzed Suzuki-Miyaura cross-coupling of 6-bromo- and 6,8-dibronno-1,2,3,4-tetrahydroquinolines, 5-bromo-8-methoxyquinoline, and 5,7-dibromo-8-methoxyquinoline with substituted phenylboronic acids affords the corresponding 6-aryl- (13a-d), 6,8-diaryl- (14a-c), 5-aryl- (15), and 5,7-diaryl- (16b, c) tetrahydroquinolines and quinolines in high yields (68%-82%). The structures of all the products are characterized by H-1 NMR, C-13 NMR, F-1(9) NMR, and Fourier transform infrared spectroscopy and by elemental analysis.