The reactions of (phenylsulfinyl)-furans, -thiophenes, -benzofurans, and -indoles with carbon nucleophiles in the presence of trifluoroacetic anhydride allowed the nucleophilic installation of carbon functional groups on these π-sufficient heteroaromatic nuclei. These reactions were initiated by their aromatic Pummerer-type reactions to generate highly electrophilic sulfonium intermediates, to which nucleophilic addition of carbon nucleophiles proceeded to give the products. The complete regioselectivity was attained in every case depending on the position of the sulfinyl group of the substrates, and the sulfur functional groups remaining on the products were utilized for the installation of the second carbon substituents at their ipso-position. These features make the developed method unique among a variety of existing carbon–carbon bond forming reactions of these π-sufficient heteroatomatics.
