Access to Spiro-bicyclo[2.1.1]hexanes via BF3∙Et2O-Catalyzed Formal [2π + 2σ] Cycloaddition of Bicyclo[1.1.0]butanes with Benzofuran-derived Oxa(aza)dienes

21 March 2024, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


Herein, we have developed a method for the construction of spiro[benzofuran-2,2'-bicyclo[2.1.1]hexanes] via BF3·Et2O-catalyzed formal [2π + 2σ] cycloaddition of bicyclo[1.1.0]butanes with benzofuran-derived oxa(aza)dienes. This transformation allowed for facile access to a variety of functionalized spiro-bicyclo[2.1.1]hexanes in good yields (up to 99% yield) with excellent regioselectivities and a broad substrate scope (34 examples) under mild reaction conditions. Moreover, the synthetic utility of the cycloadducts were further emphasized through a scale-up experiment and subsequent synthetic transformations.


dipolar cycloaddition
strained molecules
bicyclic compounds

Supplementary materials

Supporting Information
Rapid access of diverse spiro[benzofuran-2,2'-bicyclo[2.1.1]hexanes] via BF3·Et2O-catalyzed [2π + 2σ] cycloaddition of bicyclo[1.1.0]butanes with readily available benzofuran-derived oxa(aza)dienes.


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