The dissertation deals with the synthesis of fused-heterocycle-ring-system which are potential candidates for applications in organic materials and pharmacology. Site-selective Suzuki reactions of polyhalogenated substrates with o-bromophenylboronic acid followed by two-fold C-N cross-coupling reactions afforded the final products. The physical properties were investigated and explained based on DFT theoretical calculations. Moreover, biscarbazoles were synthesized via C-N coupling and C-H bond activation as key steps.