New preparation of tridentate bis-oxazoline carbazole ligand effective for enantioselective nozaki-hiyama reaction

A new preparation of the tridentate bis-oxazoline carbazole ligand 1 is described. This method features direct formation of the amide, which is a precursor of the ligand l, via the Pd-catalyzed amidation and following BF₃ · OEt₂ mediated oxazoline formation. This method required only 2 steps from the aryl iodide to form the bis-oxazoline ligand; hence, it would be generally used for preparing other bis-oxazoline ligands.