A Dual-Catalysis Anion-Binding Approach to the Kinetic Resolution of Amines: Insights into the Mechanism via a Combined Experimental and Computational Study
摘要:
Racemic benzylic amines undergo kinetic resolution via benzoylation with benzoic anhydride in the presence of a dual catalyst system consisting of a readily available amide-thiourea catalyst and 4-dimethylaminopyridine (DMAP). An evaluation of various experimental parameters was performed in order to derive a more detailed understanding of what renders this process selective. The catalyst's aggregation behavior and anion-binding ability were evaluated in regard to their relevance for the catalytic process. Alternate scenarios, such as catalyst deprotonation or the in situ formation of a neutral chiral acylating reagent were ruled out. Detailed computational studies at the M06/6-31G(d,p) level of theory including solvent modeling utilizing a polarized continuum model provide additional insights into the nature of the ion pair and reveal a range of important secondary interactions that are responsible for efficient enantiodiscrimination.
Merging Nucleophilic and Hydrogen Bonding Catalysis: An Anion Binding Approach to the Kinetic Resolution of Propargylic Amines
摘要:
An efficient kinetic resolution of primary propargylic amines with s-factors of up to 56 is reported. The strategy is based on a dual catalytic approach, namely the use of a newly developed and easy-to-make thiourea-amide anion binding catalyst in combination with 4-(dimethylamino)pyridine (DMAP), both employed at a 5 mol% catalyst loading. Benzylic amines are also resolved with s-factors of up to 38.
A Dual-Catalysis Anion-Binding Approach to the Kinetic Resolution of Amines: Insights into the Mechanism via a Combined Experimental and Computational Study
摘要:
Racemic benzylic amines undergo kinetic resolution via benzoylation with benzoic anhydride in the presence of a dual catalyst system consisting of a readily available amide-thiourea catalyst and 4-dimethylaminopyridine (DMAP). An evaluation of various experimental parameters was performed in order to derive a more detailed understanding of what renders this process selective. The catalyst's aggregation behavior and anion-binding ability were evaluated in regard to their relevance for the catalytic process. Alternate scenarios, such as catalyst deprotonation or the in situ formation of a neutral chiral acylating reagent were ruled out. Detailed computational studies at the M06/6-31G(d,p) level of theory including solvent modeling utilizing a polarized continuum model provide additional insights into the nature of the ion pair and reveal a range of important secondary interactions that are responsible for efficient enantiodiscrimination.
A Dual-Catalysis Anion-Binding Approach to the Kinetic Resolution of Amines: Insights into the Mechanism via a Combined Experimental and Computational Study
作者:Nisha Mittal、Katharina M. Lippert、Chandra Kanta De、Eric G. Klauber、Thomas J. Emge、Peter R. Schreiner、Daniel Seidel
DOI:10.1021/jacs.5b00190
日期:2015.5.6
Racemic benzylic amines undergo kinetic resolution via benzoylation with benzoic anhydride in the presence of a dual catalyst system consisting of a readily available amide-thiourea catalyst and 4-dimethylaminopyridine (DMAP). An evaluation of various experimental parameters was performed in order to derive a more detailed understanding of what renders this process selective. The catalyst's aggregation behavior and anion-binding ability were evaluated in regard to their relevance for the catalytic process. Alternate scenarios, such as catalyst deprotonation or the in situ formation of a neutral chiral acylating reagent were ruled out. Detailed computational studies at the M06/6-31G(d,p) level of theory including solvent modeling utilizing a polarized continuum model provide additional insights into the nature of the ion pair and reveal a range of important secondary interactions that are responsible for efficient enantiodiscrimination.
Merging Nucleophilic and Hydrogen Bonding Catalysis: An Anion Binding Approach to the Kinetic Resolution of Propargylic Amines
作者:Eric G. Klauber、Chandra Kanta De、Tejas K. Shah、Daniel Seidel
DOI:10.1021/ja105337h
日期:2010.10.6
An efficient kinetic resolution of primary propargylic amines with s-factors of up to 56 is reported. The strategy is based on a dual catalytic approach, namely the use of a newly developed and easy-to-make thiourea-amide anion binding catalyst in combination with 4-(dimethylamino)pyridine (DMAP), both employed at a 5 mol% catalyst loading. Benzylic amines are also resolved with s-factors of up to 38.