A novel ion pair catalyst containing a chiral counteranion can be readily derived by simply mixing cinchona alkaloid-derived diamine with chiral camphorsulfonic acid (CSA). A mixture of 9-amino(9-deoxy)epi-quinine 8 and (−)-CSA was found to be the best catalyst with matching chirality, enabling the direct amination of α-branched aldehydes to proceed in quantitative yields and with nearly perfect enantioselectivities
只需将
金鸡纳
生物碱衍生的二胺与手性
樟脑磺酸(CSA)混合,即可轻松获得新型的含有手性抗衡离子的离子对催化剂。发现9-
氨基(9-脱氧)表-
奎宁8和(-)-CSA的混合物是具有匹配手性的最佳催化剂,可以使α-支化醛的直接胺化以定量收率进行,并且几乎完美对映选择性。0.5mol%的催化剂负载量足以催化反应,并且已经成功地证明了克数规模的对
生物重要的α-甲基苯基甘
氨酸的对映选择性合成。