Kobe Pharmaceutical University, Motoyamakita, Higashinada, Kobe 658-8558, Japan.
Org Lett. 2020 Dec 4;22(23):9249-9252. doi: 10.1021/acs.orglett.0c03465. Epub 2020 Nov 16.
A Brønsted acid-mediated synthesis of pyrazoles from conjugated hydrazones through a β-protonation/nucleophilic addition/cyclization/aromatization sequence was developed. This protocol utilizing the ambiphilic reactivity of hydrazones enables not only self-condensation but also cross-condensation, affording multisubstituted pyrazoles in high yields, with a broad substrate scope. This sequential reaction proceeds under mild conditions via a simple operation. Moreover, the method can be applied to the synthesis of a nonsteroidal anti-inflammatory drug, Lonazolac.
发展了一种通过β-质子化/亲核加成/环化/芳构化序列，由共轭腙合成吡唑的布朗斯特酸介导的方法。该方案利用腙的两性反应性，不仅能够进行自缩合，还能够进行交叉缩合，以高收率提供多取代吡唑，具有广泛的底物范围。该串联反应通过简单操作在温和条件下进行。此外，该方法可用于非甾体抗炎药Lonazolac 的合成。
