Chiral Zn(II)-Bisamidine Complex as a Lewis-Brønsted Combined Acid Catalyst: Application to Asymmetric Mukaiyama Aldol Reactions of α-Ketoesters
作者:Ryo Gotoh、Masahiro Yamanaka
DOI:10.3390/molecules17089010
日期:——
Lewis-Brønsted acid catalyst. The chiral Zn(II)-bisamidine catalyst prepared from the 2,2'-bipyridyl derived bisamidine ligand, ZnCl₂, and AgSbF₆ promoted asymmetric Mukaiyama aldol reaction of α-ketoester and α,α-disubstituted silyl enol ether to afford the α-hydroxyester having sequential quarternary carbons in good yield, albeit with low enantioselectivity. Addition of 1.0 equivalent of the fluoroalcohol
着眼于共振稳定脒骨架的空间和电子特性,阳离子金属-双脒配合物被设计为共轭组合路易斯-布朗斯台德酸催化剂。由 2,2'-联吡啶衍生的双脒配体、ZnCl2 和 AgSbF₆ 制备的手性 Zn(II)-双脒催化剂促进 α-酮酯和 α,α-二取代甲硅烷基烯醇醚的不对称 Mukaiyama 羟醛反应,得到 α-羟基酯尽管具有低对映选择性,但具有良好产率的连续季碳。添加 1.0 当量的具有合适酸度和体积的氟代醇可显着提高对映选择性(高达 68% ee)。DFT 计算表明,这种加成效应是由氟代醇在 Zn(II)-双脒催化剂上的自组装引起的。