Clayden Jonathan, Hennecke Ulrich
School of Chemistry, Univesity of Manchester, Oxford Road, Manchester M13 9PL, United Kingdom.
Org Lett. 2008 Aug 21;10(16):3567-70. doi: 10.1021/ol801332n. Epub 2008 Jul 22.
2-, 3- and 4-Bromopyridine, along with other brominated electron-deficient arenes, undergo palladium-catalyzed coupling with ureas of structure RNMeCONHMe. Where R is a chiral, alpha-substituted benzyl group, treatment with LDA leads to a benzylic organolithium which undergoes rearrangement with stereospecific and regiospecific transfer of the pyridyl group, generating a quaternary stereogenic center with high enantioselectivity. Alcoholysis of the urea under neutral conditions reveals the pyridyl amine.
2-、3-和4-溴吡啶,以及其他溴代缺电子芳烃,可与结构为RNMeCONHMe的脲发生钯催化偶联反应。当R为手性α-取代苄基时,用LDA处理会生成苄基有机锂,该有机锂会发生重排,吡啶基进行立体专一性和区域专一性转移,生成具有高对映选择性的季立体中心。在中性条件下对脲进行醇解可得到吡啶基胺。