Palladium Catalyzed Green Cascade Reactions Involved With Cyclic Iodonium Salt

This paper reports a novel ligand free Pd-catalyzed cascade reaction between o-chloro(hetero)aryl acids and cyclic diaryliodonium salts.It includes the following three aspects:In the first part,we reported the current progress about the synthesis and application of triphenylenes.Polycyclic aromatic hydrocarbons(PAHs),seen as segments of infinite two-dimensional graphene,have been extensively utilized as potential candidates for optoelectronic devices and ?-conjugated functional materials.Most of the practical syntheses reported to date may be classfied into six different types,these methods still suffer from different drawbacks,such as harsh conditions or limited substrate scopes,etc.In the second part,a novel ligand-free Pd-catalyzed cascade reaction between o-chlorobenzoic acids and cyclic diaryliodonium salts is reported.This one-pot procedure involves a carboxylic acid directed o-arylation followed by intramolecular decarboxylative annulation affording various valuable triphenylenes,which can be further transformed into diversified building blocks for material chemistry.For the first time,we showed that aromatic halide can reacted with diaryliodonium salts under the direction of carboxylic acid.It was also demonstrated that the carboxylic acid could be employed as both a traceless directing group and functional handle.In the third part,with commercially available pyridine acids and cyclic diaryliodonium salts as the starting materials we have developed an unprecedented site-selective synthesis of dibenzo[f,h]quinolones and their derivatives,which can be further functionalized siteselectively to afford diversified building blocks for materials chemistry.The key to this novel method is the employment of carboxylic acids as both directing groups and functional handles,together with cyclic diaryliodonium salts for this one-pot double cross-coupling reaction.