The organocatalytic asymmetric Michael addition of 2,2-dimethyl-1,3-dioxan-5-one (1) was performed with various nitro alkenes 2 using a number of proline-based catalysts (A–M) affording polyfunctional nitro ketones 3. Reverse diastereoselectivity was observed with the diphenylprolinol catalyst J, and the best diastereo- and enantiomeric excesses were achieved with the sulfonamide catalyst M (de = 84–98 %
2,2-二甲基-1,3-二恶烷-5-酮 (1) 的有机催化不对称迈克尔加成反应与各种硝基烯烃 2 一起使用多种脯
氨酸基催化剂 (A-M) 进行,得到多功能硝基酮 3。使用二苯基脯
氨醇催化剂 J 观察到反向非对映选择性,使用磺酰胺催化剂 M(de = 84-98 %,ee = 81-86 %)实现了最佳的非对映异构体和对映体过量。(© Wiley-
VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)