Coupling of Bulky, Electron-Deficient Partners in Aryl Amination in the Preparation of Tridentate Bis(oxazoline) Ligands for Asymmetric Catalysis
作者:Helen A. McManus、Patrick J. Guiry
DOI:10.1021/jo0262558
日期:2002.11.1
o-substituted coupling partners, 2-(2'-bromophenyl)oxazolines 8 and 2-(o-aminophenyl)oxazolines 9. By varying the substituent on the coupling partners, a range of 10 ligands has been prepared in good yield. During the synthesis of 2-(o-aminophenyl)oxazolines 9a-d, a number of products of unexpected side reactions were isolated in two of the three steps. Alternatively, the required 2-(o-aminophenyl)oxazolines
制备了一种新的三齿双(恶唑啉)配体7,其中N-苯基苯胺单元连接两个恶唑啉环。它们合成的关键步骤是在两个庞大的邻位取代偶合偶合剂2-(2'-溴苯基)恶唑啉8和2-(邻氨基苯基)恶唑啉9之间进行Hartwig-Buchwald型Pd催化的芳基胺化反应。作为偶联伙伴上的取代基,已经以高收率制备了10种配体。在2-(邻氨基苯基)恶唑啉9a-d的合成过程中,在三个步骤中的两个步骤中分离出了许多意想不到的副反应产物。或者,所需的2-(邻氨基苯基)恶唑啉9是通过DAST-促进的羟酰胺12a-d的环脱水而获得的,而没有形成任何副产物。