Syntheses and Applications of (Thio)Urea-Containing Chiral Quaternary Ammonium Salt Catalysts
作者:Johanna Novacek、Mario Waser
DOI:10.1002/ejoc.201301594
日期:2014.2
bifunctional (thio)urea-containing quaternary ammonium salts based on easily obtainable chiral backbones. Among the different classes of catalysts that were successfully synthesized, those based on trans-1,2-cyclohexane diamine were found to be the most powerful for the asymmetric α-fluorination of β-keto esters. Selectivities up to 93:7 could be obtained by using only 2 mol-% of the optimized catalyst. The
我们在此报告了我们基于易于获得的手性骨架获得一类新的系统修饰的含(硫)脲的季铵盐的努力。在成功合成的不同类别的催化剂中,发现基于反式-1,2-环己二胺的催化剂对β-酮酯的不对称α-氟化作用最强。仅使用 2 mol-% 的优化催化剂即可获得高达 93:7 的选择性。这些催化剂的双功能性质的重要性通过使用简化的单功能催化剂类似物的对照实验得到证明,该类似物仅产生几乎外消旋的产物。