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.
Chemistry. 2013 Nov 25;19(48):16424-30. doi: 10.1002/chem.201302122. Epub 2013 Oct 15.
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.
手性 N,N'-二氧化物/Zn(NTf2)2 配合物在温和条件下被证明能有效地催化芳基乙腈与亚甲基丙二酸二乙酯的直接不对称共轭加成反应。该反应具有广泛的底物适用性，能以中等至良好的收率、高非对映选择性（82:18->99:1 d.r.）和对映选择性（81-99%ee）得到相应产物。反应效果良好，这归因于金属三氟甲磺酰亚胺盐的高路易斯酸度和配体加速效应。N,N'-二氧化物也作为布朗斯特碱有利于脱质子过程。该催化反应可在克级规模下进行，产率、非对映选择性和对映选择性保持不变。含有官能团的产物可直接进行进一步的操作。此外，还提出了一种可能的催化模型来解释不对称诱导的起源。
