Department of Organic Chemistry, Universitat de Barcelona, Faculty of Chemistry, Martí i Franquès 1-11, 08028 Barcelona, Spain.
Chemistry. 2010 May 10;16(18):5354-61. doi: 10.1002/chem.200903025.
A new, easy, and highly enantioselective method for the synthesis of quaternary alpha-alkyl-alpha-amino acids based on organocatalysis is reported. The addition of oxazolones to 1,1-bis(phenylsulfonyl)ethylene is efficiently catalyzed by simple chiral bases or thioureas. The reaction affords alpha,alpha-disubstituted alpha-amino acid derivatives with complete C4 regioselectivity and with excellent yields and enantioselectivities. This methodology is complementary to previously reported enantioselective approaches to quaternary alpha-amino acids and allows the synthesis of alpha-phenyl-alpha-alkyl-alpha-amino acids and alpha-tert-butyl-alpha-alkyl-alpha-amino acids. It has distinct advantages in terms of operational simplicity, enviromentally friendly conditions, and suitability for large-scale reactions.
报道了一种基于有机催化的新型、简便、高对映选择性合成季碳α-烷基-α-氨基酸的方法。简单的手性碱或硫脲能有效地催化恶唑酮与 1,1-双(苯磺酰基)乙烯的加成反应。该反应以完全的 C4 区域选择性、优异的产率和对映选择性得到α,α-二取代的α-氨基酸衍生物。该方法与之前报道的季碳α-氨基酸的对映选择性方法互补，并允许合成α-苯基-α-烷基-α-氨基酸和α-叔丁基-α-烷基-α-氨基酸。该方法在操作简单、环境友好条件和适用于大规模反应方面具有明显的优势。
