Palladium-catalyzed Tandem Reactions For The Synthesis Of Dibenzonthiophenes

Dibenzothiophene is a heterocyclic structure that is more common in organic photoelectric materials,and has been widely used in organic solar cells and other fields.Compared with thiophene,dibenzothiophene has a larger conjugated ?-planar structure and can transport electrons more efficiently.The sulfur atom also has electron-donating ability,and the material often exhibits hole migration characteristics.More interestingly,if sulfur is oxidized to sulfone,these materials can exhibit electron transport properties that are poor in electronic structures.Therefore,dibenzothiophenes are one of the most interesting structures in the field of organic photoelectric materials.How to construct these compounds more effectively has also attracted the attention of synthetic chemists.Based on this application background,the work of this paper is centered on the synthesis of dibenzothiophenes.The main content is divided into the following two aspects:1.It was successfully achieved,with o-bromoiodobenzene and p-methylthiophenol as reactants,Pd(CH3CN)2Cl2 as catalyst,DPEphos as ligands,by Pd-catalyst C-S coupling and C-H bond activation.It showed good substrate compatibility in the reaction.2.Based on the cross coupling reaction of o-bromo iodobenzene and p-methylthiophenol,we used iodobenzene and o-bromothiophenol as reactants by adjusting the equivalent ratio of ligand and catalyst in the reaction.Pd(CH3CN)2Cl2 was also used as catalyst,and DPEphos as ligand.Similarly,we achieved dibenzothiophenes,by Pd-catalyzed cross coupling reaction of C-S coupling and C-H bond activation.These two methods greatly broaden the range of substrates,which made this method more practical.Compared with the traditional synthesis method and transition metal-catalyzed cyclization reaction,the above two operations are simple and easy to obtain,due to the design of the cross coupling reaction.The palladium catalyst and ligand,that we used,are also common and can be purchased commercially.In addition the reaction conditions are mild and simple;it has good functional group compatibility.Therefore,it provides a simple,flexible and efficient way for the synthesis of dibenzothiophenes and has great application value.