Reactivity of the 2-aryl-6,8-dibromo-2,3-dihydroquinolin-4(1$H)$-ones in a palladium catalyzed Sonogashira cross-coupling reaction

Authors: MALOSE JACK MPHAHLELE, Felix Adetunji OYEYIOLA

Abstract: Pd/C-PPh$_{3}$--CuI catalyzed Sonogashira cross-coupling of the 2-aryl-6,8-dibromo-2,3-dihydroquinolin-4(1$H)$-ones with phenyl acetylene or 3-butyn-1-ol afforded the corresponding 8-alkynylated quinolin-4(1$H)$-one derivatives, exclusively. Double carbo-substitution to afford the 6,8-dialkynyl derivatives was observed when PdCl$_{2}$(PPh$_{3})_{2}$ was used as Pd(0) source. The monoalkynylated derivatives were, in turn, subjected to PdCl$_{2}$ in acetonitrile under reflux to afford either the corresponding 2,4-diaryl-8-bromopyrrolo[3,2,1-\textit{ij}]quinolinones or the 8-(4-hydroxybutanoyl)-substituted quinolinone derivatives, exclusively. Suzuki--Miyaura cross-coupling of the 2-aryl-6-bromo-8-(alkynyl)quinolin-4-ones afforded the 2,4,8-trisubstituted pyrrolo[3,2,1-\textit{ij}]quinolin-6-ones.

Keywords: 2-Aryl-6, 8-dibromo-2, 3-dihydroquinolin-4(1$H)$-ones, cross-coupling, pyrrolo[3, 2, 1-\textit{ij}]quinolin-6-ones

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