Proline and α‐Methylproline as Chiral Auxiliaries for the Synthesis of Enantiopure Bis‐Cyclometalated Iridium(III) Complexes

摘要: A convenient proline- and α-methylproline-mediated method for the synthesis of enantiomerically pure bis-cyclometalated iridium(III) complexes is reported. The reactions l-proline or l-α-methylproline with [Ir(µ-Cl)(C^N)2]2 (C^N = cyclometalating 2-phenylpyridine, 2-phenylbenzoxazole, 2-phenylbenzothiazole ligand) afforded diastereomeric mixtures intermediate prolinatoiridium(III) from which Λ-(S) diastereomers were isolated excellent purity by washing, precipitation, crystallization. subsequent trifluoroacetic acid (TFA) induced substitution prolinate ligands 2,2′-bipyridine retention configuration provided chiral-only-at-metal >99 % ee.