Synthesis Of Biaryl Heterocycles Via C-H Direct Arylation Of Haloarenes

The biaryl moiety is an important structural motif existed in a large number of biological interested compounds and functional molecules, such as natural products, medicine intermediate and functional materials. Chemists have always been looking for a simple and effective pathway to couple two simple arenes directly to synthesize biaryl compounds.In the past decades, transition metal-catalyzed cross-coupling reactions to afford biaryls of a great number of organometallic agents with aryl halides have been greatly developed. Although high yields and good selectivities can be achieved through this process, multi-step preactivation of both organometallic reagents and halides wastes a lot of time which makes them less satisfactory for biaryl synthesis. Since 1980, direct arylation of arenes with aryl halides in the presence of catalytic transition metals have emerged as alternative to classic cross-coupling chemistry in biaryl synthesis. The employment of the highly versatile noble metals such as Pd, Rh, and Ru in catalytic direct arylations has become well established. Recently, the less privileged transition metals such as Cu, Ni and Fe are capable of performing the same task. Later, several pioneering rports revealed that the presence of metal catalysts is not entirely necessary to promote biaryl coupling reaction. The reports show that common transition metals as well as organic reagents can also catalyze the cross-coupling of arenes. Compared with noble metal, less privileged transition metal gave advances on the low toxicity and cost, which showed better atom economy.This paper showed our recent work on these topics, with focus on the development of biaryl synthesis via C-H direct arylation. The main contents of this thesis are as follows:Firstly, we summerized the recent development of C-H activation, in combination with researches and reviews, we proposed the biaryl synthesis via intramolecular cyclization of arenes.Secondly, 1-iodo-2-(phenoxymethyl)benzene and 1-(benzyloxy)-2-iodobenzene are choosen as the basic substrate to optimize the reaction conditions, through exploring the catalytic reagents, solvents and additives on the reaction to set up the optimal reaction condition of the reaction.Thirdly, we designed different haloarenes including a series of ethers, amines and amides to find the scope of this reaction. Additionally, we primarily investigated the influence of different function groups on efficiencies and selectivities of the reaction, and a possible mechanism was proposed to explain the reaction.