Torquoselective Nazarov Cyclization Mediated by a Chiral Sulfoxide: First Enantioselective Synthesis of two Known Anticancer Agents

Herein, we report a Nazarov cyclization reaction between activated dienones that contain an aromatic moiety as an electron-donating group and chiral sulfoxides that act as both an electron-withdrawing group and a chiral inductor. The sulfinyl group directed the torquoselectivity and AlCl3 was used as a promoter. Only the trans stereoisomers were observed. Substrates that contained activated aromatic moieties, including phenyl and aromatic heterocycles, led to the desired cyclopentenones. The potential use of this method was highlighted in the first enantioselective synthesis of two anticancer agents.