- Nickel-Catalyzed Multicomponent Coupling: Synthesis of α-Chiral Ketones by Reductive Hydrocarbonylation of Alkenes
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A nickel-catalyzed, multicomponent regio- and enantioselective coupling via sequential hydroformylation and carbonylation from readily available starting materials has been developed. This modular multicomponent hydrofunctionalization strategy enables the straightforward reductive hydrocarbonylation of a broad range of unactivated alkenes to produce a wide variety of unsymmetrical dialkyl ketones bearing a functionalized α-stereocenter, including enantioenriched chiral α-aryl ketones and α-amino ketones. It uses chiral bisoxazoline as a ligand, silane as a reductant, chloroformate as a safe CO source, and a racemic secondary benzyl chloride or an N-hydroxyphthalimide (NHP) ester of a protected α-amino acid as the alkylation reagent. The benign nature of this process renders this method suitable for late-stage functionalization of complex molecules.
- Chen, Jian,Zhu, Shaolin
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supporting information
p. 14089 - 14096
(2021/09/13)
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- Asymmetric Aza-Diels-Alder Reactions of in Situ Generated β,β-Disubstituted α,β-Unsaturated N-H Ketimines Catalyzed by Chiral Phosphoric Acids
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A novel asymmetric synthesis of dihydropyridinones with vicinal quaternary stereocenters has been realized by asymmetric aza-Diels-Alder reactions of 3-amido allylic alcohols with oxazolones enabled by chiral phosphoric acid catalysis. A series of aryl/alkyl- and alkyl/alkyl-disubstituted 3-amido allylic tertiary alcohols and 4-substituted oxazolones could be well tolerated in these reactions, producing dihydropyridinones with excellent diastereoselectivities and high enantioselectivities. Mechanistic study and control experiments were performed to shed light on the reaction mechanism, in which a configurationally defined β,β-disubstituted α,β-unsaturated N-H ketimine was proposed as the key intermediate.
- He, Shunlong,Gu, Huanchao,He, Yu-Peng,Yang, Xiaoyu
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supporting information
p. 5633 - 5639
(2020/07/14)
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- Asymmetric palladium(II)-catalyzed cascade reaction giving quaternary amino succinimides by 1,4-addition and a nef-type reaction
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Simple starting materials, high-value products: A dinuclear ferrocene-based PdII complex transforms mixtures of racemic N-benzoyl α-amino acids, nitroolefins, acetic anhydride, and manganese acetate into biologically interesting quaternary amin
- Weber, Manuel,Frey, Wolfgang,Peters, Rene
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supporting information
p. 13223 - 13227
(2014/01/06)
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- Bispalladacycle-catalyzed Michael addition of in situ formed azlactones to enones
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The development and further evolution of the first catalytic asymmetric conjugate additions of azlactones as activated amino acid derivatives to enones is described. Whereas the first-generation approach started from isolated azlactones, in the second-generation approach the azlactones could be generated in situ starting from racemic N-benzoylated amino acids. The third evolution stage could make use of racemic unprotected α-amino acids to directly form highly enantioenriched and diastereomerically pure masked quaternary amino acid products bearing an additional tertiary stereocenter. The step-economic transformations were accomplished by cooperative activation by using a robust planar chiral bis-Pd catalyst, a Br?nsted acid (HOAc or BzOH; Ac=acetyl, Bz=benzoyl), and a Br?nsted base (NaOAc). In particular the second- and third-generation approaches provide a rapid and divergent access to biologically interesting unnatural quaternary amino acid derivatives from inexpensive bulk chemicals. In that way highly enantioenriched acyclic α-amino acids, α-alkyl proline, and α-alkyl pyroglutamic acid derivatives could be prepared in diastereomerically pure form. In addition, a unique way is presented to prepare diastereomerically pure bicyclic dipeptides in just two steps from unprotected tertiary α-amino acids. Flourishing step economy: The evolution of the catalytic asymmetric addition of azlactones to enones is described. The first-generation approach started from isolated azlactones. In the second-generation approach azlactones could be generated in situ from racemic N-benzoylated amino acids. The third evolution stage could directly use racemic unprotected α-amino acids to form a large number of highly enantioenriched quaternary amino acids derivatives (see figure). Copyright
- Weber, Manuel,Jautze, Sascha,Frey, Wolfgang,Peters, René
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supporting information
p. 14792 - 14804
(2013/01/15)
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- Polyclonal antibodies: A cheap and efficient tool for screening of enantioselective catalysts
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Enantioselective polyclonal antibodies have been produced and characterized to develop a high-throughput screening method for lipase activity fingerprinting, with a view to the enantioselective hydrolysis of azlactones.
- MacOvei, Cristian,Vicennati, Paola,Quinton, Julia,Nevers, Marie-Claire,Volland, Herve,Creminon, Christophe,Taran, Frederic
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supporting information; experimental part
p. 4411 - 4413
(2012/05/20)
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- Catalytic asymmetric synthesis of functionalized α,α- disubstituted α-amino acid derivatives from racemic unprotected α-amino acids via in-situ generated azlactones
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Masked and activated highly enantioenriched α,α-disubstituted α-amino acids with an additional adjacent stereocenter were formed by a tandem reaction involving five steps using racemic unprotected amino acid substrates. Key step is the 1,4-addition of in-situ generated azlactones to a broad number of enones. The products of this step-economic route can, e.g., be useful for a divergent and rapid access to biologically interesting unnatural glutamic acid derivatives. Copyright
- Weber, Manuel,Frey, Wolfgang,Peters, Rene
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supporting information; experimental part
p. 1443 - 1449
(2012/07/13)
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- Bispalladacycle-catalyzed bronsted acid/base-promoted asymmetric tandem azlactone formation-michael addition
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Cooperative activation by a soft bimetallic catalyst, a hard Bronsted acid, and a hard Bronsted base has allowed the formation of highly enantioenriched, diastereomerically pure masked α-amino acids with adjacent quaternary and tertiary stereocenters in a single reaction starting from racemic N-benzoylated amino acids. The products can, for example, be used to prepare bicyclic dipeptides.
- Weber, Manuel,Jautze, Sascha,Frey, Wolfgang,Peters, Rene
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supporting information; experimental part
p. 12222 - 12225
(2010/11/03)
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- Composition containing a penem or carbapenem antibiotic and the use of the same
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Administration of an N-acylated amino acid in association with a penem or carbapenem antibiotic relieves or eliminates the renal problems associated with administration of the antibiotic alone. The amino acid derivative and antibiotic may be formulated together as a composition or administered separately, either simultaneously or sequentially.
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- Composition containing a penem or carbapenem antibiotic
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Administration of an N-acylated amino acid in association with a penem or carbapenem antibiotic relieves or eliminates the renal problems associated with administration of the antibiotic alone. The amino acid derivative and antibiotic may be formulated together as a composition or administered separately, either simultaneously or sequentially. The composition may be prepared by simple mixing.
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- NEW SYNTHETIC ROUTE TO N-ACYL-α-AMINO ACIDS VIA AMIDOCARBONYLATION BY MEANS OF HOMOGENEOUS BINARY CATALYST SYSTEMS
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New catalytic processes which lead to the formation of N-acyl-α-amino acids promoted by homogeneous binary systems are described: (a) the isomerization-amidocarbonylation of allylic alcohols catalyzed by transition metal binary systems, e.g., Co-Rh, Co-Pd, Co-Fe, giving various aliphatic N-acyl-α-amino acids; (b) the isomerization-amidocarbonylation of oxiranes catalyzed by cobalt-Lewis acid systems giving N-acyl-α-amino acids; The process is extremely effective for the synthesis of N-acetylphenylalanine from styrene oxide and (c) the hydroformylation-amidocarbonylation of trifluoropropene catalyzed by cobalt-rhodium binary system giving N-acetyltrifluorovaline in excellent regioselectivity and yield.Possible mechanisms for these new processes are discussed.
- Hirai, Kenji,Fujita, Makoto,Fuchikami, Takamasa
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p. 203 - 214
(2007/10/02)
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- KINETICS AND MECHANISM OF ACID HYDROLYSIS OF N-BENZOYL-L-LYSINES
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Minor differences in acid hydrolysis rates of α- and ε-amide bonds in corresponding N-benzoyl-L-lysines have been found.The reaction is accelerated in the presence of free carboxyl group in the lysine-derivative molecule.The acid dissociation constants KAH of N - and Nε-benzoyl-L-lysines have been determined.Also the substituent effect in benzoyl group on the reaction rate has been examined.A mechanism of the acid hydrolysis of acyl derivatives of lysine is proposed.
- Muzalewski, Feliks,Ciurak, Marek
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p. 931 - 940
(2007/10/02)
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- DIRECT CONVERSION OF ALLYLIC ALCOHOLS INTO N-ACYL-α-AMINO ACIDS BY CATALYTIC AMIDOCARBONYLATION BY MEANS OF HOMOGENEOUS BINARY SYSTEMS
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N-Acyl-α-amino acids are synthesized by the amidocarbonylation of allylic alcohols catalyzed by homogeneous binary systems which consist of cobalt carbonyl and rhodium (or iron or palladium) complexes.
- Hirai, Kenji,Takahashi, Yoshitaka,Ojima, Iwao
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p. 2491 - 2494
(2007/10/02)
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