Pd/C-PPh3–CuI catalyzed Sonogashira cross-coupling of the 2-aryl-6,8-dibromo-2,3-dihydroquinolin-4(1H)-ones with phenyl acetylene or 3-butyn-1-ol afforded the corresponding 8-alkynylated quinolin-4(1H)-one derivatives, exclusively. Double carbo-substitution to afford the 6,8-dialkynyl derivatives was observed when PdCl2(PPh3)2 was used as Pd(0) source. The monoalkynylated derivatives were, in turn, subjected to PdCl2 in acetonitrile under reflux to afford either the corresponding 2,4-diaryl-8-bromopyrrolo[3,2,1-ij]quinolinones or the 8-(4-hydroxybutanoyl)-substituted quinolinone derivatives, exclusively. |
