Synthesis of Spiropentadiene Pyrazolones by Rh(III)-Catalyzed Formal sp³ C–H Activation/Annulation

A Rh-catalyzed enol-directed formal sp3 C–H activation/annulation of α-arylidene pyrazolones with alkynes has been developed. This reaction provides a convenient route to synthesize spiropentadiene pyrazolones in good to excellent yields at room temperature, exhibiting good functional group tolerance, gram scalability, and high regioselectivity. Of note, the α-arylidene pyrazolone was introduced as a novel C3 synthon in C–H activation/annulation.开发了一种铑（Rh）催化、以烯醇为导向基团的α-亚芳基吡唑酮与炔烃的形式sp³ C-H键活化/环化反应。该反应可在室温条件下以良好至优异的收率便捷制备螺戊二烯吡唑酮类化合物，同时展现出优异的官能团耐受性、克级放大能力与较高的区域选择性。值得关注的是，本研究首次将α-亚芳基吡唑酮作为一种新型C3合成子应用于C-H键活化/环化反应中。