Recent Developments in Polyene Cyclizations and Their Applications in Natural Product Synthesis

Abstract

Cascade polyene cyclization reactions are highly efficient and elegant bioinspired transformations that involve simultaneous multiple bond constructions to rapidly generate complex polycyclic molecules. This review summarizes the most prominent work on a variety of cationic and radical cascade cyclizations and their applications in natural product synthesis published between 2014 and 2018. 1 Introduction 2 Cationic Polyene Cyclizations 2.1 Lewis Acid Mediated Polyene Cyclizations 2.2 Bronsted Acid Mediated Polyene Cyclizations 2.3 Halogen Electrophile Initiated Polyene Cyclizations 2.4 Sulfur Electrophile Initiated Polyene Cyclizations 2.5 Transition-Metal-Mediated Cationic Polyene Cyclizations 3 Radical Polyene Cyclizations 3.1 Transition-Metal-Mediated Radical Polyene Cyclizations 3.2 Photocatalyst-Mediated Polyene Cyclizations 4 Origin of Stereocontrol in Polyene Cyclizations 5 Conclusion.