Achieving conformational control over C–C, C–N and C–O bonds in biaryls, N,N′-diarylureas and diaryl ethers: advantages of a relay axis

Abstract
The orientation of Ar–C, Ar–N and Ar–O bonds in biaryls, N,N′-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.