Synthesis Of 9,10 - Di - Substituted Phenanthrene By 2,2 '' - Dibromobiphenyl And Alkynes Catalyzed By Palladium - Catalyzed Coupling

The polycyclic aromatic hydrocarbons (PAHs) as an important class of π-conjugated materials has been widely applied in organic semiconductor, liquid crystals, solar cell, light emitters and so on. Studies on polycyclic aromatic hydrocarbons have always been a hot research topic in theoretical chemistry, organic synthesis and material science. The development of high efficient synthetic methodologies for polycyclic aromatic hydrocarbons is very important for the design of novel organic functional materials and improvement of performance. Phenanthrene belongs to a typical PAHs, and many π-conjugated functional materials such as picene and carbon nanotubes contain a phenanthrene motif. Some phenanthrene derivatives have exhibited excellent superconductivity, photoconductivity properties as well as interesting biological activities.Traditional constuctions of phenanthrene derivatives mainly rely on multiple-step reactions, polymerition of arynes as well as double couplings between 1,4-dimetallic reagents and dihaloarenes. The efficiency of multiple-step reactions is low; The aryne intermediate is very active and the reaction process is difficult to control; The synthesis of organic bimetallic reagents is in low yield and at high cost, especially for Rh etc. Although these methods provide multiple choices for the synthesis of phenanthrenes, there still exist several problems. In recent years, the reported transition metal-catalyzed annulations of biphenyl derivatives, especially using 2,2’-diiodobiphenyls with alkynes are the most economic and synthetically most attractive for the easily prepared or commercially available substances, low reaction cost, high efficiency and widespread functional group tolerance. For the high reactivities of some organometallic reagents, the tolerance of functional groups was generally low. Thereofore, the development of efficient and low cost synthetic routes to the phenanthrenes is highly valuable.In 1994, Dyker synthesized the 9,10-diphenylphenanthrene and its derivatives with diphenyl acetylene and iodobenzene as the model reaction. Because of using an excess alkyne in the reaction, the byproduct of 1,2,3,4-Tetraphenylnaphthalene was generated, which resulting in very low yield of substituted phenanthrene. In 2012, Wu reported the Pd-catalyzed coupling tandem cyclization between 2,2’-iodobiphenyl and alkynes for the synthesis of 9,10-disubstituted phenanthrene in high yields. However, only iodobiphenyls showed unique reactivity towards alkynes and successfully afforded the phenanthrenes, attempts of using their analogues such as 2-bromobiphenyl and 2,2’-dibromobiphenyl failed to undergo the annulation. Therefore, to realize the coupling cyclization process between bromobiphenyl and alkynes for synthesis of phenanthrene derivatives is a great challenge and still significant for the gererality and low cost of this methodology.In this thesis, we synthesize the 9,10-disubstituted phenanthrene derivatives via palladium-catalyzed coupling cyclization process between 2,2-dibromobiphenyl and diaryl acetylenes, aryl/heteroaryl acetylenes and aryl/alkyl acetylenes. In our study, 9,10-disubstitued phenanthrenes could be obtained in high yields using only 1.1 equivalents of alkynes with 5 mol% Pd(PPh3)2Cl2 and 6 mol% Xantphos. Still, dibenzo chrysenes were also successfully synthesized from 9,10-diaryl-substituted phenanthrenes via Scholl reaction with an oxidant. The thesis consists of three chapters.The first chapter introduces the mechanism, application and the study progress of the coupling reaction; the progress of alkyne coupling cyclization; the research advances of 9,10-disubstituted phenanthrene and the thesis’s purpose and significance.The second chapter, based on sonogashira coupling reaction,14 kinds of interminal alkynes and 2,2’-dibromobiphenyl have been synthesized.The third chapter, usinging diphenyl acetylene and 2,2’-dibromo-biphenyl as a template reactions, we screened the reaction parameters; Based on the optimal reaction conditions,20 kinds of 9,10-disubstituted phenanthrene have been generated with the substituted diphenyl acetylene and biphenyl halides; Two dibenzo chrysenes were synthesized using 9,10-diaryl-substituted phenanthrenes via Scholl reaction.