Institute of Natural Sciences and Mathematics, Ural Federal University, 51 Lenina Ave., 620000 Ekaterinburg, Russian Federation.
Org Biomol Chem. 2018 Mar 7;16(10):1692-1707. doi: 10.1039/c7ob02725g.
Chemo- and regiocontrolled syntheses of pyrazoles and pyridones are presented on the basis of 4-pyrones. A novel approach towards highly functionalized 3,4'-bipyrazoles has been developed by using reactions of ethyl 5-acylcomanoates with hydrazines. The acid-promoted double cyclocondensation allows switching of the structure of the pyrazole rings easily through changing both the nature of hydrazine and the reaction conditions. The transformation of 4-pyrones with phenylhydrazine in EtOH at -20 °C leads to hydroxypyridones as monoaddition products which can be used as precursors for the preparation of pyridone and pyrazole derivatives. A novel rearrangement of 2-hydroxypyridone to pyrazolyl-1,3-diketones in DMSO was found. The structure and regiochemistry of bipyrazoles were confirmed by X-ray analysis and 2D NMR experiments.
基于 4-吡喃酮，本文提出了吡唑和吡啶酮的化学和区域控制合成方法。通过使用乙 5-酰基马来酸酯与肼的反应，开发了一种合成高官能化 3,4'-联吡唑的新方法。酸促进的双重环缩合允许通过改变肼的性质和反应条件轻松切换吡唑环的结构。在-20°C 的 EtOH 中用苯肼处理 4-吡喃酮，得到作为单加成产物的羟基吡啶酮，可作为制备吡啶酮和吡唑衍生物的前体。在 DMSO 中发现了 2-羟基吡啶酮到吡唑基-1,3-二酮的新型重排。通过 X 射线分析和 2D NMR 实验证实了双吡唑的结构和区域化学。
