Axially Dissymmetric Diphosphines in the Biphenyl Series: Synthesis of (6,6′-Dimethoxybiphenyl-2,2′-diyl)bis(diphenylphosphine)(‘MeO-BIPHEP’) and Analogues<i>via</i>an<i>ortho</i>-Lithiation/Iodination<i>Ullmann</i>-Reaction Approach
作者:Rudolf Schmid、Joseph Foricher、Marco Cereghetti、Peter Schönholzer
DOI:10.1002/hlca.19910740215
日期:1991.3.13
The new axially dissymmetric diphosphines (R)- and (S)-(6,6′-dimethoxybiphenyl-2,2′-diyl)bis(diphenyl phosphine) ((R)- and (S)-5a; ‘MeO-BIPHEP’) and the analogues (R)- and (S)-5b and 5c have been synthesized in enantiomerically pure form. These ligands have become readily available by a synthetic scheme which employs, as key steps, an ortho-lithiation/iodination reaction of the (m-methoxyphenyl)diprienylphosphine
新的轴向不对称二膦(R)-和(S)-(6,6'-二甲氧基联苯-2,2'-二基)双(二苯基膦)((R)-和(S)-5a ;'MeO-BIPHEP )和类似物(R)-和(S)-5b和5c已经以对映体纯的形式合成。这些配体通过其采用,作为关键步骤,合成方案变得容易获得的邻-lithiation /碘化(的反应米甲氧基苯基)diprienylphosphine氧化物8和随后的乌尔曼所得碘化物的反应9提供外消旋的双(氧化膦)10。随后将双(氧化膦)10与(-)-(2 R,3 R)-和(+)-(2 S,3 S)-O -2,3-二苯甲酰基酒石酸分解,还原为二膦5。在乌尔曼反应构成对2,2'-双(膦酰基) -取代的联苯系统一个新的和有效的路由。通过X射线分析衍生的Pd配合物(R,R)-17a和(5b和5c)建立(R)-5a的绝对构型。分别通过对衍生的Pd配合物16或17的1 H-NMR比较,以及通过CD比