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Proline and α‐Methylproline as Chiral Auxiliaries for the Synthesis of Enantiopure Bis‐Cyclometalated Iridium(III) Complexes
Author(s) -
Helms Melanie,
Wang Chuanyong,
Orth Barbara,
Harms Klaus,
Meggers Eric
Publication year - 2016
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201600260
Subject(s) - chemistry , enantiopure drug , diastereomer , iridium , trifluoroacetic acid , proline , walden inversion , ligand (biochemistry) , enantioselective synthesis , stereochemistry , medicinal chemistry , racemization , metal , combinatorial chemistry , organic chemistry , amino acid , catalysis , biochemistry , receptor
A convenient proline‐ and α‐methylproline‐mediated method for the synthesis of enantiomerically pure bis‐cyclometalated iridium(III) complexes is reported. The reactions of l ‐proline or l ‐α‐methylproline with [Ir(µ‐Cl)(C^N) 2 ] 2 (C^N = cyclometalating 2‐phenylpyridine, 2‐phenylbenzoxazole, or 2‐phenylbenzothiazole ligand) afforded diastereomeric mixtures of intermediate prolinatoiridium(III) complexes from which the Λ‐( S ) diastereomers were isolated with excellent diastereomeric purity by washing, precipitation, or crystallization. A subsequent trifluoroacetic acid (TFA) induced substitution of the prolinate ligands with 2,2′‐bipyridine with the retention of configuration provided the chiral‐only‐at‐metal complexes with >99 % ee .