Toward Safer Processes for C−C Biaryl Bond Construction: Catalytic Direct C−H Arylation and Tin-Free Radical Coupling in the Synthesis of Pyrazolophenanthridines
作者:Susana Hernández、Isabel Moreno、Raul SanMartin、Germán Gómez、María Teresa Herrero、Esther Domínguez
DOI:10.1021/jo902257j
日期:2010.1.15
pyrazolo[1,5-f]phenanthridine derivatives has been efficiently synthesized by a short, straightforward sequence. A tandem amine-exchange/heterocyclization of enaminones was successfully applied to the regioselective preparation of 1,5-diarylpyrazole intermediates with structure resemblance to relevant nonsteroidal anti-inflammatory drugs such as celecoxib or tepoxalin. The final key step, cyclization by intramolecular
一系列吡唑并[1,5- f通过短而直接的序列已有效地合成了]菲啶衍生物。烯胺酮的串联胺交换/杂环化已成功用于区域选择性制备1,5-二芳基吡唑中间体,其结构类似于相关的非甾体类抗炎药,如celecoxib或tepoxalin。最后的关键步骤是通过分子内双芳基键形成进行环化,这是通过两种替代方法完成的:自由基偶联和通过CH活化的催化直接芳基化。探讨了这两种方法的范围和局限性,并确定了它们的互补性。另外,已经将聚合物负载的多相催化剂与均相类似物进行了比较。在激进的过程中,