Racemic 2,2â²-bis(pyridin-2-yl)-1,1â²-binaphthalene (±)-6 was prepared in four synthetic steps from 2-naphthol. Resolution of the novel atropisomeric ligand 6 was effected by repeated preparation, recrystallisation and then liberation of the bis-tartrate salt (D and L). This affords both enantiomers of 6 (>96% enantiomeric excess, ee) whose absolute configurations were assigned by CD. The ligand 6 is stable towards racemisation (ÎGâ¡rac > 167 kJ molâ1) and the structure was confirmed by single crystal X-ray diffraction of the complex [ZnCl2(6)]. The structure and stereodynamics of the complex [Pd(η3-C3H5)(6)][OTf] (OTf = O3SCF3) which comprises a C2-symmetric ligand bound via Pd to a non-C2-symmetric allyl fragment was studied in detail in solution by 1-D and 2-D 1H NMR and in the solid state by single crystal X-ray diffraction. Apparent stereodynamic processes of the allyl ligand, as detected in solution by NMR, are shown to arise from ligand 6 stereodynamics and exchange. The ligand 6 represents the first compound/building block for a series of enantiomerically pure N,N-ligands that may be of utility in supramolecular co-ordination chemistry and in asymmetric catalysis.
对映体2,2′-双(
吡啶-2-基)-1,1′-双
萘(±)-6是从
2-萘酚通过四个合成步骤制备而成。新型的对映异构体
配体6的分解是通过重复的制备、重结晶以及随后释放双
酒石酸盐(D和L)实现的。这提供了6的两个对映体(对映体纯度超过96%,ee),其绝对构型通过圆二色性(CD)被确定。
配体6在对映互变方面是稳定的(ΔG‡rac > 167 kJ mol⁻¹),其结构通过复合物[ZnCl2(6)]的单晶X射线衍射得到了确认。复合物[Pd(η³-
C3H5)(6)][OTf](OTf = O3SCF3)的结构和立体动力学在溶液中通过一维和二维¹H NMR以及在固态中通过单晶X射线衍射进行了详细研究。通过NMR在溶液中检测到的烯丙基
配体的明显立体动力学过程表明,源于
配体6的立体动力学及其交换。
配体6代表了一系列光学纯的N,N-
配体的第一个化合物/构件,这些
配体在超分子配位
化学和不对称催化中可能具有应用价值。