title: Chiral-Zn(NTf2)2-complex-catalyzed diastereo- and enantioselective direct conjugate addition of arylacetonitriles to alkylidene malonates.
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.
authors.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.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Yao
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Liu
authors.forename: Peng
authors.initials: P
authors.lastname: He
authors.forename: Yin
authors.initials: Y
authors.lastname: Zhu
authors.forename: Xiangjin
authors.initials: X
authors.lastname: Lian
authors.forename: Lili
authors.initials: L
authors.lastname: Lin
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Feng
keywords: asymmetric catalysis; conjugate addition; enantioselectivity; ligand effects; zinc