我们报告了通过使用手性恶唑啉助剂将原位生成的芳基锂和芳烃偶联来制备轴向立体富集的联苯。芳炔前体的设计、恶唑啉的选择和反应条件是获得所需的、高度取代的、富含阻转异构的二芳基产物的关键。在一种情况下,可以通过柱色谱分离和通过 X 射线晶体学建立的绝对构型以异构纯形式获得两种阻滞非对映体。反应的立体选择性似乎受微妙的参数控制。
Atropo-diastereoselective coupling of aryllithiums and arynes — variations around the chiral auxiliary
作者:David Augros、Boubacar Yalcouye、Anaïs Berthelot-Bréhier、Matthieu Chessé、Sabine Choppin、Armen Panossian、Frédéric R. Leroux
DOI:10.1016/j.tet.2016.01.047
日期:2016.8
The atropo-selective coupling of in situ generated arynes and aryllithiums bearing various chiralauxiliaries ortho to lithium (tert-butylsulfoxide, para-tolylsulfoxide, tartrate-derived chiral diethers and oxazolines) is described. Chiral oxazolines showed the best results in terms of yields of coupling products. Different reaction parameters like the nature of the aryne precursor, the oxazoline,
The asymmetric Ullmann reaction III. Application of a first-order asymmetric transformation to the synthesis of C2-symmetric chiral, non-racemic biaryls
作者:Todd D. Nelson、A.I. Meyers
DOI:10.1016/s0040-4039(00)76879-1
日期:1994.5
Heating a diastereomeric mix of (62:38) chiral biaryls with Cu-ion resulted in a (93:7) mix of diastereomers.
The ellagitannins are galloyl esters of glucose that contain at least one chiral biaryl (digalloyl) subunit. Included in this family are the tellimagrandins (1-3). The first asymmetric synthesis of (S)-4,4',5,5',6,6'-hexamethoxy-2,2'-diphenic acid, a ubiquitous subunit in ellagitannins, is reported by utilization of an intermolecular oxazoline-mediated asymmetric Ullmann coupling. Attachment of this acid to an appropriate glucose core resulted in the synthesis of an ellagitannin.
Nelson Todd D., Meyers A. I., Tetrahedron Lett, 35 (1994) N 20, S 3259-3262