This general reaction, which takes place under traditional Pummerer rearrangement reaction conditions (TFAA), produces sulfenylation products cleanly in good to excellent yields when R is a simple alkyl group (R = CH3, C2H5). This process is thought to proceed via a mechanism similar to the Pummerer rearrangement.  except that nucleophilic attack occurs at sulfur before the elimination reaction to a thionium ion for the Pummerer rearrangement pathway takes place (eqn. 2). In all cases we have examined to date, the nucleophilic source has been the pi-electron rich pyrrole ring, tethered in some fashion to the sulfoxide moiety.