Heteroaromatic ethers of phenols in nickel-catalysed ipso-replacement reactions with magnesium, zinc and tin organometallic compounds
作者:Amadeu F. Brigas、Robert A. W. Johnstone
DOI:10.1039/b001333l
日期:——
Phenols are readily converted in high yield into the heterocyclic ethers, 5-aryloxy-1-phenyl-1H-tetrazole, 1 and 3-aryloxy-1λ6,2-benzothiazole 1,1-dioxide, 2. X-Ray crystallographic analysis and other evidence shows that, in these ethers, the originally strong phenolic C–OH bond is considerably weakened on derivatization. In nickel-catalysed cross-coupling reactions with organozinc and organotin compounds, the heterocyclic parts of ethers 1,2 provide good nucleofuges. In similar cross-coupling reactions with organomagnesium halides, ethers 1 again provide good nucleofuges but, in marked contrast, ethers 2 do not. In all reactions, palladium based catalysts were mostly not effective.
酚类物质很容易以高产率转化为杂环醚,即 5-芳氧基-1-苯基-1H-四氮唑 1 和 3-芳氧基-1λ6,2-苯并噻唑 1,1-二氧化物 2。X 射线晶体分析和其他证据表明,在这些醚中,原本牢固的酚类 C-OH 键在衍生化过程中被大大削弱。在镍催化的与有机锌和有机锡化合物的交叉耦合反应中,醚 1、2 的杂环部分提供了良好的核诱导。在与有机镁卤化物的类似交叉偶联反应中,醚 1 也能提供良好的核赋形剂,但与此形成鲜明对比的是,醚 2 却不能。在所有反应中,钯基催化剂大多不起作用。