Programmed synthesis of tetraarylthiophenes through sequential C-H arylation.

A general protocol for the programmed synthesis of tetraarylthiophenes has been established. The utilization of three catalysts, RhCl(CO){P[OCH(CF(3))(2)](3)}(2), PdCl(2)/P[OCH(CF(3))(2)](3), and PdCl(2)/bipy, enables regioselective sequential arylations at the three C-H bonds of 3-methoxythiophene with iodoarenes. Interesting metal- and ligand-controlled regiodivergent C-H arylations have been uncovered during this study. The installation of fourth aryl groups to the thus-generated 2,4,5-triaryl-3-methoxythiophenes has been accomplished through a sequence of demethylation, triflation, and Suzuki-Miyaura coupling.