First Synthesis of 5- and 7-Phenylethynyl-8-hydroxyquinolines by Sonogashira Reaction

5-Chloro-7-(2-phenylethynyl)quinolin-8-ol and 7-iodo-5-(2 -phenylethynyl)quinolin-8-ol was synthesized by Pd-CuI catalyzed Sonogashira-type cross-coupling of 8-(benzyloxy)-5-chloro-7-iodoquinoline and 8-(benzyloxy)-5,7- diiodoquinoline with 1-ethynylbenzene. The coupling products were smoothly debenzylated by boron trichloride in dichloromethane to afford the corresponding products in good yields.