Recent Developments in Asymmetric Nazarov Reactions

:: The Nazarov reaction involves the cyclization of divinyl ketones into cyclopentenones under the influence of strong acids. The prevalence of five-membered carbocycles in a multitude of natural and bioactive products has triggered an intense development of efficient methods for their construction. In particular, asymmetric versions of the Nazarov reaction are achieved by using either a chiral auxiliary or a chiral catalyst, which can be an organocatalyst, a metal catalyst, or a multicatalytic system. This review aims to update the field of asymmetric Nazarov reactions published in 2017. It is divided into four sections, dealing successively with Nazarov reactions of chiral auxiliaries, organocatalytic enantioselective Nazarov reactions, metal/boron-catalyzed enantioselective Nazarov reactions, and multicatalytic enantioselective Nazarov reactions. Each section of the review is subdivided into simple asymmetric Nazarov reactions and Nazarovbased domino/tandem reactions, which have allowed numerous more complex functionalized chiral molecules to be synthesized in one-pot procedures.