<i>N</i>,<i>N′</i>-Diarylureas: A New Family of Atropisomers Exhibiting Highly Diastereoselective Reactivity

2,6-Disubstituted N-aryl ureas rotate slowly about their ArN bonds and can exist as separable atropisomers. They also react remarkably diastereoselectively, with the urea axis controlling new stereogenic centers with high fidelity in a variety of nucleophilic and electrophilic addition reactions. The sense of diastereoselectivity in lateral lithiationelectrophilic quench reactions is electrophile-dependent and appears to be the result of stereospecific reaction with one of two interconvertible diastereoisomeric organolithiums.