Novel Bifunctionalization of Activated Methylene: Base‐Promoted Trifluoromethylthiolation of β‐Diketones with Trifluoromethanesulfinyl Chloride

A novel bifunctionalization of activated methylene was achieved successfully through the base‐promoted trifluoromethylthiolation of β‐diketones or β‐ketoesters with trifluoromethanesulfinyl chloride. A series of α‐trifluoromethylthiolated α‐chloro‐β‐diketones and α‐chloro‐β‐ketoesters were obtained in moderate to good yields under mild conditions. When β‐diketones containing a phenyl group with a hydroxyl or amino substituent at the ortho position were used as substrates, intramolecular trifluoromethylthiolation/cyclization reaction took place to give the corresponding cyclic products. Furthermore, the protocol could be extended to perfluoroalkylthiolation with the sodium perfluoroalkanesulfinate/POCl 3 system. On the basis of experimental results, plausible mechanisms are proposed.