Study On The Synthesis Of C₂-symmetric Five-member Ring Heterocycle-fused Polyaromatic Compounds

Polycyclic aromatic cpompounds with extended π conjugated system are attracting numerous attention due to their important roles in the field of optoelectronic materials,especially in the area of organic small molecule field effect transistor(OFETs).The introduction of five-membered heterocycles such as furan or thiophene can effectively improve the solubility of polyaromatic aromatic compounds,while the cooperation of nitrogen atoms can enhance their stabilities.In this dissertation,we designed and synthesized a series of furan and phenazine-based phenanthrenes and fused diaryl-substituted dibenzocarbazoles.In the first part,9,10-phenanthrenequinone as raw material was brominated with Bromine to afford 3,6-dibromo-9,10-phenanthrenequinone,which was reduced by sodium dithionate,followed by the reaction with dimethyl sulfate to form 3,6-dibromo-9,10-dimeothxuyphenanthrene.It was further performed nucleophilic substitution with MeONa/MeOH to afford 3,6,9,10-tetramethoxy-phenanthrene,which was subsequently oxidized with Ceric ammonium nitrate(CAN)in acetonitrile to obtain 3,6-dimethoxy-9,10-phenanthrenequinone,it was converted into 2,7-diiodo-3,6-dimethoxy-9,10-phenanthrenequinone with NIS.2,7-Diiodo-3,6-dimethoxy-9,10-phenanthrenequinone was demethylated by BBr3 to give methyl 2,7-diiodo-3,6-dihydroxy-9,10-phenanthrenequinone,which reacted with o-phenylenediamine to lead to the formation of be 2,7-diiodo-3,6-dihydroxy-substituted dibenzophenazine.Finally,(Ph3P)2PdCl2-catalyzed Sonogashira coupling/ring closure reaction was carried out with various alkynes to complete C2-symmetrical bis(benzofuran)-[5,6-a;6’,5’-c]phenazines.In the second part,the Fisher indole synthesis between 2-tetralone and hydrazine hydrate was conducted to obtain 6,7,8,9-tetrahydro-5H-dibenzo[c,g]carbazole,which was dehydrogenated on Pd/C to afford 7/H-dibenzo[c,g]carbazole.The bromination of 5/H-dibenzo[c,g]carbazole with NBS resulted in the formation of 5,9-dibromo-7/H-dibenzo[c,g]carbazole,which was reacted with different arylboronic acids by Pd-132-calatyzed Suzuki coupling to form 5,9-diaryl-7/H-dibenzo-[c,g]carbazoles efficiently and with high yields.