Lewis Acid Catalyzed Cycloaddition Reaction of Bicyclo[1.1.0]butanes

Abstract In recent years, formal cycloaddition reactions involving bicyclo[1.1.0]butanes (BCBs) have furnished an array of innovative methodologies and strategies for the efficient synthesis of bicyclo[2.1.1]hexanes (BCHs). Most methods can be broadly classified into two main modes: the radical pathway and the two-electron pathway. This Synpacts article will summarize the recent advancements in Lewis acid catalyzed formal cycloaddition reactions involving BCBs with alkenes, dipolar molecules, and alkynes, spanning the period from 2022 to 2024. Additionally, we introduce the formal cycloaddition reaction of BCBs with ynamides, catalyzed by Sc(OTf)3, which has been recently developed by our group. This approach offers a novel and efficient method for the synthesis of polysubstituted 2-amino-bicyclo[2.1.1]hexenes. 1 Introduction 2 Lewis Acid Catalyzed Formal Cycloaddition of BCBs with Alkenes and Dipoles 3 Lewis Acid Catalyzed Formal Cycloaddition of BCBs with Alkynes 4 Conclusion