The orientation of ArâC, ArâN and ArâO bonds in biaryls, N,Nâ²-diarylureas and diaryl ethers (whose conformers are distinguishable by NMR) may be controlled with a selectivity up to >95 : 5 by an adjacent stereogenic centre; the selectivity may be greater when a second stereogenic axis is inserted between the controlling centre and the slowly rotating bond.
芳基-碳、芳基-氮和芳基-氧键在
联苯、N,N'-二芳基
脲和二芳基醚(其构象可通过核磁共振区分)中的取向,可以被相邻的手性中心以高达>95:5的选择性控制;当在控制中心和缓慢旋转的键之间插入第二个手性轴时,选择性可能会更高。