(R)- and (S)-6,6′-dimethyl- and 6,6′-dimethoxy-2,2′-diiodo-1,1′-biphenyls: Versatile intermediates for the synthesis of atropisomeric diphosphine ligands
作者:Marco Cereghetti、Wolf Arnold、Emil A. Broger、Alain Rageot
DOI:10.1016/0040-4039(96)01090-8
日期:1996.7
Starting from enantiomerically pure 6,6′-dimethyl- or 6,6′-dimethoxy-2,2′-diiodo-1,1′-biphenyls (1a or 1b) a variety of atropisomeric diphosphine ligands of defined axial chirality are directly accessible in good yields: asymmetric diphosphines of type B and the corresponding diphosphines with one (type C) or two (type D) stereogenic phosphorus atoms. Pitfalls of the lithiation/phosphination reaction
从对映体纯的6,6'-二甲基或6,6'-二甲氧基-2,2'-diiodo-1,1'-联苯(1a或1b)开始,可以直接获得各种具有轴向手性的阻转异构二膦配体收率高:B型不对称二膦和具有一个(C型)或两个(D型)立体磷原子的相应二膦。讨论了锂化/磷化反应的陷阱。通过热差向异构可以减少P-手性非对映异构体的数量。