CuBr2‑Mediated One-Pot Synthesis of Sulfonyl 9‑Fluorenylidenes

In this article, a high-yield method for the synthesis of sulfonyl 9-fluorenylidenes is described, which consists of a one-pot straightforward three-step synthetic route, including (i) CuBr2-mediated α-bromination of o-arylacetophenone, (ii) sequential nucleophilic substitution of the resulting α-bromo o-arylacetophenone with sodium sulfinate (RSO2Na), and (iii) the CuBr2-mediated intramolecular Friedel–Crafts cyclizative dehydration. A plausible mechanism is proposed and discussed. This protocol provides a highly effective regio- and stereoselective annulation via the formation of one carbon–carbon (C–C) bond and one carbon–sulfur (C–S) bond.