Synthesis, separation and structure determination of atropisomeric ketimines: precursors of new potential chiral ligands and phase-transfer catalysts

Sterically crowded chiral biaryl ketimines have been prepared via nucleophilic addition onto a substituted benzonitrile or 8-cyanoquinoline and subsequent treatment of the resulting methylenimines either with methyl iodide, or with a chiral primary amine. Atropisomerism due to the hindered rotation of the aryl groups about the C-C bond adjacent to CN has been evidenced in all cases. Physical separation and full characterisation (NMR and X-ray analysis) of atropisomeric imines have been accomplished.