Palladium-catalyzed synthesis and fluorescence study of 2,3-diaryl-5-ethynylbenzo[e]indoles

A series of new ethynylated benzoindoles were synthesized starting with the nucleophilic attack of naphthoquinone by lithium acetylides. The resulting 1,4-diethynylnaphthalenes were applied in palladium catalyzed CN coupling - hydroamination domino reactions. The obtained compounds fluoresce in the near ultraviolet and blue spectral region with high quantum yields (65–78%).