N,N'-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.
Clayden
Jonathan
J
School of Chemistry, University of Manchester, Manchester, UK. clayden@man.ac.uk
Turner
Hazel
H
Helliwell
Madeleine
M
Moir
Elizabeth
E