title: Chiral Recognition and Dynamic Thermodynamic Resolution of Sulfoxides by Chiral Iridium(III) Complexes.
abstract: The optically active Ir(III) complex Λ-[Ir(ppy)2(MeCN)2](PF6) (ppy is 2-phenylpyridine) with a chiral-at-metal was first demonstrated to preferentially react with (R)-configuration sulfoxides 2-(alkylsulfinyl)phenol (HLO-R, R = Me, Et,iPr, and Bn) rather than (S)-configuration sulfoxides under thermodynamic equilibrium due to the hydrogen-bonding interaction and the differences in the steric interference, and thus act as a highly efficient enantioreceptor for resolution of sulfoxide enatiomers. Treatment of Λ-[Ir(ppy)2(MeCN)2](PF6) with 2 equiv of rac-HLO-R offered (S)-HLO-R in yields of 46-47% with 97-99% enantiomeric excess (ee) values and Λ-[Ir(ppy)2{(S)-LO-R}] complex in yields of 89-93% with 98% diastereomeric excess (de). The (R)-HLO-R chiral sulfoxides were obtained by the acidolysis of Λ-[Ir(ppy)2{(S)-LO-R}] complexes with trifluoroacetic acid (TFA) in the presence of coordinated solvent MeCN in yields of 45-47% with 98-99% ee values. Moreover, the enantioreceptor Λ-[Ir(ppy)2(MeCN)2](PF6) can be recycled in a yield of 86-91% with complete retention of the configuration at metal center and can be reused in a next reaction cycle without loss of reaction activity and enantioselectivity. The absolute configurations at the metal centers and sulfur atoms were determined by X-ray crystallography.
authors.affiliation: MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry, Sun Yat-Sen University , Guangzhou 510275, China.
authors.forename: Su-Yang
authors.initials: SY
authors.lastname: Yao
authors.affiliation: MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry, Sun Yat-Sen University , Guangzhou 510275, China.
authors.forename: Xing-Yang
authors.initials: XY
authors.lastname: Chen
authors.affiliation: MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry, Sun Yat-Sen University , Guangzhou 510275, China.
authors.forename: Yan-Ling
authors.initials: YL
authors.lastname: Ou
authors.affiliation: MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry, Sun Yat-Sen University , Guangzhou 510275, China.
authors.forename: Bao-Hui
authors.identifier: http://orcid.org/0000-0003-0990-6661
authors.initials: BH
authors.lastname: Ye