Structure-Based Analysis and Optimization of a Highly Enantioselective Catalyst for the Strecker Reaction
作者:Petr Vachal、Eric N. Jacobsen
DOI:10.1021/ja027246j
日期:2002.8.1
asymmetric Streckerreaction catalyzed by a metal-free Schiff base catalyst was conducted. The active site of the catalyst, the relevant stereoisomer of the imine substrate, and the solution structure of the imine-catalyst complex were elucidated using a series of kinetics, structure-activity, and NMR experiments. An unusual bridging interaction between the imine and the urea hydrogens of the catalyst was
Enantioselective Catalytic Addition of HCN to Ketoimines. Catalytic Synthesis of Quaternary Amino Acids
作者:Petr Vachal、Eric N. Jacobsen
DOI:10.1021/ol005636+
日期:2000.3.1
Highly enantioselective addition of HCN to ketoimines has been achieved for the first time using readily accessible and recyclable Schiff base catalysts. Essentially quantitative isolated yield and enantioselectivity of up to 95% ee was obtained. Furthermore, some of the Strecker adducts could be recrystallized in high recovery, yielding optically pure materials. Conversion of the alpha-aminonitrile adducts to the corresponding alpha-quaternary alpha-amino acids was effected in high yield by a formylation/hydrolysis sequence.