Chiral‐Zn(NTf2)2‐Complex‐Catalyzed Diastereo‐ and Enantioselective Direct Conjugate Addition of Arylacetonitriles to Alkylidene Malonates |
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Authors: | Jingjing Yao Prof. Dr. Xiaohua Liu Peng He Yin Zhu Xiangjin Lian Dr. Lili Lin Prof. Dr. Xiaoming Feng |
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Affiliation: | Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064 (P.R. China), Fax: (+86)?28‐8541‐8249 |
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Abstract: | Chiral N,N′‐dioxide/Zn(NTf2)2 complexes were demonstrated to be highly effective in the direct asymmetric conjugate addition of arylacetonitriles to alkylidene malonates under mild conditions. A wide range of substrates were tolerated to afford their corresponding products in moderate‐to‐good yields with high diastereoselectivities (82:18–>99:1 d.r.) and enantioselectivities (81–99 % ee). The reactions performed well, owing to the high Lewis acidity of the metal triflimidate and a ligand‐acceleration effect. The N,N′‐dioxide also benefited the deprotonation process as a Brønsted base. The catalytic reaction could be performed on the gram‐scale with retention of yield, diastereoselectivity, and enantioselectivity. The products that contained functional groups were ready for further manipulation. In addition, a possible catalytic model was proposed to explain the origin of the asymmetric induction. |
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Keywords: | asymmetric catalysis conjugate addition enantioselectivity ligand effects zinc |
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