Synthesis Of Aza-Fused Aromatic Compounds

Fused polycyclic aromatic hydrocarbons (PAHs) have recently received numerous attention due to their potentials as materials to evaluate the properties in opto-electronics. Acenes are among the most promising organic semiconductors for application in electronic devices such as organic light-emitting diodes (OLEDs) and organic field-effect transistors (OFETs). Due to their rigid planar backbones and extended π-conjugation, ladder-type acenes exhibit particularly intense luminescence, high charge-carrier mobility as well as unique self-assembly properties. Incorporation of heteroatom(s) such as nitrogen or chalcogen into skeletons of ladder-type acenes represents an synthetic strategy for efficiently tuning the solid-state packing, molecular opto-electronic properties and significant improvement of material stability.The first part of this thesis is about the synthesis of dibenzo[c,i][1,10]-phenanthrolines via Suzuki coupling and condensation. The reaction of o-phenylenediamine with thionyl chloride affords benzo[2,1,3]thiadiazole, which was brominated with Br2 to obtain 4,7-dibromobenzo[2,1,3]thiadiazole. The palladium-catalyzed Suzuki couplings between 4,7-dibromobenzo[2,1,3]thiadiazole and various arylboronic acid or arylboronic ester to furnish 4,7-diarylbenzo[2,1,3]thiadiazoles which were deprotected with metal reductant (LiAlH4 or NaBH4/CoCl2·6H2O), followed by acid-catalyzed cyclization to obtain the target dibenzo[c,i][1,10]-phenanthrolines.The second part is focused on the synthesis of novel 5,12-diaza-dibenzo[a,h] anthracenes. The dehydration of o-nitrophenylacetic acid with DCC/DMAP afford 1,3-bis(2-nitrophenyl)acetone, which reacted with bicyclo[2.2.1]hepta-2,5-diene via retro-Diels-Alder addition to obtain the key intermediate 1,4-bis(2-nitrophenyl)fluorenone. Then the precursor is under iron reduction to afford 1,4-bis(2-aminophenyl)fluorenone which was acylated with alkyl or aroyl chlorides to obtain amides. Finally, the target molecules are obtained via the Bischler-Napieralski reaction with P2O5/POC13.