A series of 5,10-dihydroindolo[3,2-b]indoles was successfully prepared by an efficient two-step strategy based on site-selective Pd-catalyzed cross-coupling reaction with N-methyl-2,3-dibromoindole and subsequent cyclization by two-fold Pd-catalyzed C–N coupling with amines. The products show a strong fluorescence.
![Graphical abstract: Novel synthesis of 5-methyl-5,10-dihydroindolo[3,2-b]indoles by Pd-catalyzed C–C and two-fold C–N coupling reactions](http://hg.y866.cn/compound/lib/scimg/usr/1/C4OB01723D.jpg)