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

Abstract

In this article, a high-yield method for the synthesis of sulfonyl 9fluorenylidenes is described, which consists of a one-pot straightforward three-step synthetic route, including (i) CuBr 2 -mediated α-bromination of o-arylacetophenone, (ii) sequential nucleophilic substitution of the resulting α-bromo o-arylacetophenone with sodium sulfinate (RSO 2 Na), and (iii) the CuBr 2 -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.