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 chemoselectivities and a broad substrate scope (34 examples) under mild reaction conditions. Moreover, the synthetic utility of the cycloadducts was further emphasized through a scale-up experiment and subsequent synthetic transformations.

中文翻译：

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通过 BF3·Et2O 催化双环[1.1.0]丁烷与苯并呋喃衍生的氧杂(氮杂)二烯的形式[2π + 2σ]环加成反应获得螺双环[2.1.1]己烷


在此，我们开发了一种通过 BF ₃ ·Et ₂ O 催化的缩甲醛构建螺[苯并呋喃-2,2′-双环[2.1.1]己烷]的方法双环[1.1.0]丁烷与苯并呋喃衍生的氧杂(氮杂)二烯的[2π + 2σ]环加成反应。这种转化允许在温和的反应条件下以良好的收率（高达 99% 收率）轻松获得各种官能化螺环双环[2.1.1]己烷，并具有优异的化学选择性和广泛的底物范围（34 个实例）。此外，通过放大实验和随后的合成转化，进一步强调了环加合物的合成效用。