Jacobsen’s Catalyst for Hydrolytic Kinetic Resolution: Structure Elucidation of Paramagnetic Co(III) Salen Complexes in Solution via Combined NMR and Quantum Chemical Studies

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• 作者：Sebastian Kemper^† ; ; Peter Hrobrik^‡ ; ; Martin Kaupp*^&#167 ; ; Nils E. Schlrer*^† ;
• 刊名：Journal of the American Chemical Society
• 出版年：2009
• 出版时间：April 1, 2009
• 年：2009
• 卷：131
• 期：12
• 页码：4172-4173
• 全文大小：152K
• 年卷期：v.131,no.12(April 1, 2009)
• ISSN：1520-5126

文摘

NMR investigation of chiral Co(III) salen catalysts, important for enantioselective hydrolytic kinetic resolution (HKR), revealed the presence of a paramagnetic high-spin Co(III) species, which is in solvent- and temperature-dependent equilibrium with the known diamagnetic low-spin Co(III) complex. Combined with quantum chemical DFT calculations, the para- and diamagnetic chemical shifts were used to study the salen ligand conformation of the para- and diamagnetic complexes, resulting in a mechanistic proposal for the enantioselective step in catalysis.