A novel, highly stereoselective gold-catalyzed spirocyclization of 2-benzyl-3-alkynyl chromone with nitrone is described. This cascade reaction involves gold-catalyzed cycloisomerization, nitrone-olefin [3 + 2]-annulation, alkene oxidation, and rearrangement for the formation of spirocyclic products. Interestingly, the isoxazolidine ring generated from [3 + 2]-annulation donates oxygen to alkene to generate a new pyran-3(4H)-one and azetidine ring for dispiro-benzofuran formation upon heating. This work demonstrates the one-pot, gold-catalyzed, multiple-step reaction, and the reaction temperature directly affects the formation of spirocyclic products.

中文翻译：

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通过金催化级联反应进行 2-苄基-3-炔基色酮与硝酮的立体选择性双螺环化


描述了一种新型的、高度立体选择性的金催化 2-苄基-3-炔基色酮与硝酮的螺环化反应。该级联反应涉及金催化的环异构化、硝酮-烯烃[3+2]-成环、烯烃氧化以及形成螺环产物的重排。有趣的是，由[3 + 2]-环化生成的异恶唑烷环将氧提供给烯烃，生成新的吡喃-3(4 H )-酮和氮杂环丁烷环，在加热时形成二螺-苯并呋喃。这项工作展示了金催化的一锅多步反应，反应温度直接影响螺环产物的形成。