Atropselective Dibrominations of a 1,1′‐Disubstituted 2,2′‐Biindolyl with Diverging Point‐to‐Axial Asymmetric Inductions. Deriving 2,2′‐Biindolyl‐3,3′‐diphosphane Ligands for Asymmetric Catalysis
作者:Thomas Baumann、Reinhard Brückner
DOI:10.1002/anie.201806294
日期:2019.3.26
atropselectively—because of point‐to‐axial asymmetric inductions—and atropdivergently, exhibiting up to 95 % (M)‐ and as much (P)‐atropselectivity. This route to atropisomerically pure biaryls is novel and should extend to other substrates and/or different functionalizations. The dibromobiindolyls (M)‐ and (P)‐18 a furnished the biindolyldiphosphanes (M)‐ and (P)‐14 without atropisomerization. These syntheses did
在1 H NMR时标上,带有(R)配置的(1-烷氧基丙)-2-基,(1-羟基丙)-2-基或(1-甲硅烷氧基)-2-基取代基的2,2'-二吲哚基在C-1和C-1'处,在<0°C时对映异构稳定,在> 30°C时互变。此类2,2'-二吲哚基(R,R)‐17 a和非手性(!)溴化试剂可提供对映异构稳定的3,3′‐二溴二吲哚基(M)‐和/或(P)‐18 a由于点到轴的不对称感应,充其量最多只能是atropselective,而atropdivergent最多可以表现出95%(M)和同样高的(P)各向异性。这种向阻转异构的纯联芳基的途径是新颖的,并且应该扩展到其他底物和/或不同的官能化。二溴联二吲哚基(M)‐和(P)‐18 a提供了二吲哚基二膦烷(M)‐和(P)‐14,没有阻转异构化。这些合成不需要拆分外消旋混合物,这使它们与迄今为止已知的几乎所有联芳基二膦合成都不同。(M)‐和(P)‐14在催化不对