A facile, efficient, and general synthetic method for the construction of 3,4-diiododihydrothiophenes has been developed via the electrophilic iodocyclization of various S-hydroxy-2-butynyl ethanethioates. Application of the resulting iodine-containing products in organic transformations has been investigated.
A general protocol for the programmed synthesis of tetraarylthiophenes has been established. The utilization of three catalysts, RhCl(CO)P[OCH(CF3)(2)](3)}(2), PdCl2/P[OCH(CF3)(2)](3), and PdCl2/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.