Palladium-catalysed C-H arylation of benzophospholes with aryl halides.

A palladium-catalysed C-H arylation of benzophospholes with aryl halides has been developed. The reaction with aryl iodides and bromides proceeds well even under phosphine ligand-free Pd(OAc) 2 catalysis whereas the Pd(PCy 3 ) 2 is effective for the coupling with less reactive aryl chlorides. The optimal conditions are also applicable to the double arylations with organic dihalides and annulation reaction with ortho -dihalogenated benzenes, making the corresponding benzophosphole-based acceptor-donor-acceptor-type molecules and highly condensed heteroacene-type molecules of potent interest in materials chemistry. Although there are many reports of catalytic C-H functionalisations of related benzoheteroles such as indoles, benzothiophenes, and benzofurans, this is the first successful example of the catalytic direct C-H transformation of benzophospholes, to the best of our knowledge. The preliminary optoelectronic properties of some newly synthesized benzophosphole derivatives are also investigated.