Three Groups Good, Four Groups Bad? Atropisomerism in ortho‐Substituted Diaryl Ethers

Bring on the substitute: Even outside of macrocyclic structures, such as vancomycin, appropriate substitution can give rise to atropisomerism in diaryl ethers. Stereochemical stability about the ArOAr axis at room temperature or above is possible when neither of the rings is symmetrically substituted and when at least one ring carries an ortho tert-butyl group or equivalent.