Revisiting the Ullmann−Ether Reaction: A Concise and Amenable Synthesis of Novel Dibenzoxepino[4,5-<i>d</i>]pyrazoles by Intramolecular Etheration of 4,5-(<i>o,o</i>‘-Halohydroxy)arylpyrazoles
作者:Roberto Olivera、Raul SanMartin、Fátima Churruca、Esther Domínguez
DOI:10.1021/jo025767j
日期:2002.10.1
approach based on the palladium-catalyzed biaryl-ether linkage formation (Buchwald-Hartwig reaction) was also successfully applied, offering limitations with regard to the steric demand of the substituents. The synthesis of the key o,o'-halohydroxy-4,5-diarylpyrazole intermediates proceeds through the construction of the heterocyclic ring by a tandem amine-exchange/heterocyclization sequence of 3-N,N-(dimethylamino)-1
通过在CuBr.DMS介导的o,o'-卤代羟基-4,5-二芳基吡唑上进行分子内Ullmann-醚反应,完成了一系列新的二苯并氧杂庚并[4,5-d]吡唑的简洁合成。基于钯催化的联芳基醚键形成(Buchwald-Hartwig反应)的另一种有用的方法也已成功应用,这对取代基的空间需求提供了限制。关键的o,o'-卤代羟基-4,5-二芳基吡唑中间体的合成是通过3-N,N-(二甲基氨基)-1,2-的串联胺交换/杂环化序列构建杂环而进行的二芳基丙烯酮与苯肼,然后进行碱性水解以进行脱保护。烯氨基酮前体可从便宜的水杨醛或苯乙酸衍生物开始,由相应的O-磺酰氧基和O-苯甲酰氧基邻位取代的1,2-二芳基酮方便地制备。已经完成了针对外周和中枢神经系统受体的初步结合亲和力实验,结果为阴性。