Novel chiral thiazoline‐containing N―O ligands in the asymmetric addition of diethylzinc to aldehydes: substituent effect on the enantioselectivity |
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Authors: | Zhiyong Gong Qingwen Liu Pengchong Xue Kechang Li Zhiguang Song Zaiqun Liu Yinghua Jin |
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Institution: | 1. Department of Organic Chemistry, College of Chemistry, Jilin University, , Changchun, 130021 China;2. Key Laboratory for Molecular Enzymology, Engineering of the Ministry of Education, Jilin University, , Jinlin, 130012 China |
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Abstract: | Several novel chiral thiazoline primary and tertiary alcohols were easily synthesized from commercially available l ‐cysteine in three steps and with high yield. These ligands were subsequently applied to the asymmetric addition of diethylzinc (Et2Zn) to various aldehydes. Products with S configuration were obtained when thiazoline‐containing tertiary alcohol ligands were used as catalysts. The primary alcohol induced corresponding products with R configuration in 68% enantiomeric excess, which was a higher value relative to other N―O ligands possessing a primary alcohol unit in the literature. Furthermore, a plausible transition state model was proposed to explain the observed enantioselectivities. Copyright © 2012 John Wiley & Sons, Ltd. |
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Keywords: | thiazoline chiral ligands imino primary alcohol asymmetric addition diethylzinc |
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