Described herein are compounds of formula (I), related compositions, and their use, for example in the formation of α-amino acids or a precursor thereof such as an α-aminonitrile.
Scaleable catalytic asymmetric Strecker syntheses of unnatural α-amino acids
作者:Stephan J. Zuend、Matthew P. Coughlin、Mathieu P. Lalonde、Eric N. Jacobsen
DOI:10.1038/nature08484
日期:2009.10
but it is still a challenge to obtain non-natural amino acids. Alkene hydrogenation is broadly useful for the enantioselective catalytic synthesis of many classes of amino acids, but it is not possible to obtain α-amino acids bearing aryl or quaternary alkyl α-substituents using this method. The Strecker synthesis—the reaction of an imine or imine equivalent with hydrogen cyanide, followed by nitrile
Brønsted acid activation of α-diazo imide: a syn-selective glycolate Mannich reaction
作者:Timothy L. Troyer、Hubert Muchalski、Jeffrey N. Johnston
DOI:10.1039/b913785h
日期:——
A novel α-diazo imide reagent and its activation by strong Brønsted acid is shown to produce the product of a syn-glycolate Mannich transform with high diastereoselection.
Mechanism of Amido-Thiourea Catalyzed Enantioselective Imine Hydrocyanation: Transition State Stabilization via Multiple Non-Covalent Interactions
作者:Stephan J. Zuend、Eric N. Jacobsen
DOI:10.1021/ja9058958
日期:2009.10.28
An experimental and computational investigation of amido-thiourea promoted imine hydrocyanation has revealed a new and unexpected mechanism of catalysis. Rather than direct activation of the imine by the thiourea, as had been proposed previously in related systems, the data are consistent with a mechanism involving catalyst-promoted proton transfer from hydrogen isocyanide to imine to generate diastereomeric iminium/cyanide ion pairs that are bound to catalyst through multiple noncovalent interactions; these ion pairs collapse to form the enantiomeric alpha-aminonitrile products. This mechanistic proposal is supported by the observation of a statistically significant correlation between experimental and calculated enantioselectivities induced by eight different catalysts (P << 0.01). The computed models reveal a basis for enantioselectivity that involves multiple stabilizing and destabilizing interactions between substrate and catalyst, including thiourea-cyanide and amide-iminium interactions.