Alemán José, Milelli Andrea, Cabrera Silvia, Reyes Efraim, Jørgensen Karl Anker
Danish National Research Foundation Center for Catalysis, Department of Chemistry, Aarhus University, 8000 Aarhus C, Denmark.
Chemistry. 2008;14(35):10958-66. doi: 10.1002/chem.200802030.
An easy and simple synthetic approach to optically active alpha,alpha-quaternary alpha-amino acids using asymmetric organocatalysis is presented. The addition of oxazolones to nitroalkenes catalyzed by thiourea cinchona derivatives provides the corresponding alpha,alpha-quaternary alpha-amino acid derivatives with good yields, excellent diastereoselectivities (up to 98 % dr), and from moderate to good enantioselectivities (up to 92 % ee). The reaction can be performed on a large scale. The optically active oxazolone-nitroalkene addition products can be opened in a one-pot reaction to the corresponding ester-amide derivatives. Additional transformations are also presented, such as the synthesis of amino esters, amino acids, and transformation into 3,4-disubstituted pyrrolidin-2-ones.
本文介绍了一种利用不对称有机催化合成光学活性α,α-季碳α-氨基酸的简便方法。由硫脲金鸡纳碱衍生物催化的恶唑酮与硝基烯烃的加成反应能够以良好的产率、优异的非对映选择性（高达98%的dr值）以及中等至良好的对映选择性（高达92%的ee值）得到相应的α,α-季碳α-氨基酸衍生物。该反应可进行大规模操作。光学活性的恶唑酮-硝基烯烃加成产物能够在一锅反应中开环生成相应的酯-酰胺衍生物。文中还介绍了其他转化反应，如氨基酯、氨基酸的合成以及转化为3,4-二取代吡咯烷-2-酮。
