Chiral Proton-Transfer Shuttle Catalysts Promoted Enantio-selective Nazarov Cyclization.

The Nazarov cyclization reaction is a convenient, widely used method for the synthesis of cyclopentenones. In this account, we reviewed our recent efforts on the chiral proton-transfer shuttle catalysts promoted enantioselective Nazarov cyclization. We have synthesized various chiral cyclopenta[ b ]indoles and chiral α,α′-disubstituted cyclopentenones by means of cooperative catalysis of a Lewis acid and a chiral spiro phosphoric acid. The mechanistic studies revealed that the chiral spiro phosphoric acid acts as a multifunctional catalyst: it co-catalyzes the cyclization of the dienone and enantioselectively catalyzes a proton-transfer reaction of the enol intermediate via a hydrogen--bonding network. 1 Introduction 2 Enantioselective Nazarov Cyclization of Indole Enones 3 Enantioselective Silicon-Directed Nazarov Cyclization 4 Conclusion [ABSTRACT FROM AUTHOR]