Stereospecific Intramolecular Arylation of 2- and 3‑Pyridyl Substituted Alkylamines via Configurationally Stable α‑Pyridyl Organolithiums

Treatment of N′-aryl
urea derivatives of
enantiomerically enriched α-(2-pyridyl) and α-(3-pyridyl)­alkylamines
with a base leads to the migration of the N′-aryl
substituent from N to C in a ‘nonclassical’ intramolecular
nucleophilic aromatic substitution reaction. Both electron-rich and
-poor rings migrate successfully. A new quaternary stereogenic center
is formed adjacent to the pyridine ring with high stereospecificity,
even when the intermediate anion is a presumably planar 2-picolyllithium.
Base hydrolysis of the urea gives enantiomerically enriched α-pyridylalkylamines.