作者:Yves Janin、Sandrine Guillou、Frédéric Bonhomme
DOI:10.1055/s-0028-1083186
日期:——
The condensation between alkyl acetoacetates and hydrazines constitutes the very well-known Knorr synthetic method leading to pyrazol-3/5-ones. However, contemporary reports describe an alternate reaction pathway leading to low yields of 3/5-alkoxypyrazoles using hydrazine salts. No general method for the selective synthesis of 3-alkoxypyrazoles has been reported to date, hence we focused on this side reaction in an attempt to turn it into the main transformation. Depending on the starting material, various 3-alkoxypyrazoles (methoxy, ethoxy, benzyloxy, isopropoxy, allyloxy) were obtained in up to 56% yield.
烷基乙酰乙酸酯与肼之间的缩合反应构成了著名的Knorr合成方法,生成吡唑-3/5-酮。然而,近期报告描述了一种替代反应路径,使用肼盐得到的3/5-烷氧基吡唑产量较低。目前尚未报告用于选择性合成3-烷氧基吡唑的一般方法,因此我们集中研究这一副反应,试图将其转化为主要转化反应。根据起始材料的不同,获得了多种3-烷氧基吡唑(甲氧基、乙氧基、苄氧基、异丙氧基、烯丙氧基),产率高达56%。