An efficient method for the diversity-oriented synthesis of spiropentadiene pyrazolones and 1H-oxepino[2,3-c]pyrazoles is reported. The methodology attributes O-acylation of phosphorus zwitterions which were formed by a tandem phospha-1,6-addition of PBu₃ to α,β,γ,δ-unsaturated pyrazolones, further generating betaine intermediates that preferentially resulted in the aforementioned cyclic products in a diversity-oriented manner. The mechanistic investigations revealed that formation of the betaines is the key step to provide the products via an intramolecular Wittig reaction or an unprecedented δ-C-acylation/cyclization/Wittig reaction.

中文翻译：

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双向共轭吡唑啉酮通过分子内Wittig反应定向合成螺旋戊二烯吡唑啉酮和1H-氧杂环庚烷[2,3-c]吡唑。

报道了一种高效的方法来合成螺环戊二烯吡唑啉酮和1 H-氧代庚并[2,3- c ]吡唑。该方法学归因于将PBu ₃串联磷酸1,6-加成到α，β，γ，δ-不饱和吡唑酮上形成的两性磷的O-酰化作用，进一步产生了甜菜碱中间体，该中间体优先产生上述环状产物以多元化为导向的方式。机理研究表明，甜菜碱的形成是通过分子内维蒂希反应或空前的δ- C-酰化/环化/维蒂希反应提供产物的关键步骤。