- Synthesis of enantiomers of indanoxazolidinone based on the lipase-catalyzed resolution of the corresponding N-carbamylamino derivative
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Enantiomerically enriched (4R,5S)- and (4S,5R)-indano[1,2-d]oxazolidinones were enzymatically prepared from (±)-1-amino-2-indanol. Racemic 1-(N′-chloroacetyl-N-carbamylamino)-2-indanol O-chloroacetate was hydrolyzed with immobilized Pseudomonas cepacia lipase in the presence of β-cyclodextrin in acetone-buffer solution, to afford (1S,2R)-1-(N′-chloroacetyl-N-carbamylamino)-2-indanol (90%e.e.) and the unreacted (1R,2S)-substrate (97%e.e.), in nearly quantitative yields. The deprotection provided enantiomers of 1-N-carbamylamino-2-indanol, the precursor of indanoxazolidinone, via nitrosation-deaminocyclization reaction.
- Suzuki, Masumi,Nagasawa, Chiaki,Sugai, Takeshi
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- Catalytic enantioselective synthesis of β-amino alcohols by nitrene insertion
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Chiral β-amino alcohols are important building blocks for the synthesis of drugs, natural products, chiral auxiliaries, chiral ligands and chiral organocatalysts. The catalytic asymmetric β-amination of alcohols offers a direct strategy to access this class of molecules. Herein, we report a general intramolecular C(sp3)-H nitrene insertion method for the synthesis of chiral oxazolidin-2-ones as precursors of chiral β-amino alcohols. Specifically, the ring-closing C(sp3)-H amination of N-benzoyloxycarbamates with 2 mol% of a chiral ruthenium catalyst provides cyclic carbamates in up to 99% yield and with up to 99% ee. The method is applicable to benzylic, allylic, and propargylic C-H bonds and can even be applied to completely non-activated C (sp3)-H bonds, although with somewhat reduced yields and stereoselectivities. The obtained cyclic carbamates can subsequently be hydrolyzed to obtain chiral β-amino alcohols. The method is very practical as the catalyst can be easily synthesized on a gram scale and can be recycled after the reaction for further use. The synthetic value of the new method is demonstrated with the asymmetric synthesis of a chiral oxazolidin-2-one as intermediate for the synthesis of the natural product aurantioclavine and chiral β-amino alcohols that are intermediates for the synthesis of chiral amino acids, indane-derived chiral Box-ligands, and the natural products dihydrohamacanthin A and dragmacidin A.[Figure not available: see fulltext.].
- Zhou, Zijun,Tan, Yuqi,Shen, Xiang,Ivlev, Sergei,Meggers, Eric
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p. 452 - 458
(2020/12/31)
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- Versatile Cp*Co(III)(LX) Catalyst System for Selective Intramolecular C-H Amidation Reactions
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Herein, we report the development of a tailored cobalt catalyst system of Cp*Co(III)(LX) toward intramolecular C-H nitrene insertion of azidoformates to afford cyclic carbamates. The cobalt complexes were easy to prepare and bench-stable, thus offering a convenient reaction protocol. The catalytic reactivity was significantly improved by the electronic tuning of the bidentate LX ligands, and the observed regioselectivity was rationalized by the conformational analysis and DFT calculations of the transition states. The superior performance of the newly developed cobalt catalyst system could be broadly applied to both C(sp2)-H and C(sp3)-H carbamation reactions under mild conditions.
- Chang, Sukbok,Jung, Hoimin,Kim, Dongwook,Lee, Jeonghyo,Lee, Jia,Park, Juhyeon
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supporting information
p. 12324 - 12332
(2020/08/06)
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- Tuning Triplet Energy Transfer of Hydroxamates as the Nitrene Precursor for Intramolecular C(sp3)-H Amidation
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Reported herein is the design of a photosensitization strategy to generate triplet nitrenes and its applicability for the intramolecular C-H amidation reactions. Substrate optimization by tuning physical organic parameters according to the proposed energy transfer pathway led us to identify hydroxamates as a convenient nitrene precursor. While more classical nitrene sources, representatively organic azides, were ineffective under the current photosensitization conditions, hydroxamates, which are readily available from alcohols or carboxylic acids, are highly efficient in accessing synthetically valuable 2-oxazolidinones and γ-lactams by visible light. Mechanism studies supported our working hypothesis that the energy transfer path is mainly operative.
- Chang, Sukbok,Jung, Hoimin,Keum, Hyeyun,Kweon, Jeonguk
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p. 5811 - 5818
(2020/04/10)
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- Synthesis of oxazolidinones: Rhodium-catalyzed C-H amination of: N -mesyloxycarbamates
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N-Mesyloxycarbamates undergo intramolecular C-H amination reactions to afford oxazolidinones in good to excellent yields in the presence of rhodium(ii) carboxylate catalysts. The reaction is performed under green conditions and potassium carbonate is used, forming biodegradable potassium mesylate as a reaction by-product. This method enables the production of electron-rich, electron-deficient, aromatic and heteroaromatic oxazolidinones in good to excellent yields. Conformationally restricted cyclic secondary N-mesyloxycarbamates furnish cis-oxazolidinones in high yields and selectivity; DFT calculations are provided to account for the observed selectivity. trans-Oxazolidinones were prepared from acyclic secondary N-mesyloxycarbamates using Rh2(oct)4. The selectivity was reverted with a cytoxazone N-mesyloxycarbamate precursor using large chiral rhodium(ii) carboxylate complexes, affording the corresponding cis-oxazolidinone. This orthogonal selectivity was used to achieve the formal synthesis of (-)-cytoxazone.
- Lebel, Hélène,Mamani Laparra, Laura,Khalifa, Maroua,Trudel, Carl,Audubert, Clément,Szponarski, Mathieu,Dicaire Leduc, Cédric,Azek, Emna,Ernzerhof, Matthias
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p. 4144 - 4158
(2017/07/10)
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- Catalytic, enantioselective N-acylation of lactams and thiolactams using amidine-based catalysts
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In contrast to alcohols and amines, racemic lactams and thiolactams cannot be resolved directly via enzymatic acylation or classical resolution. Asymmetric N-acylation promoted by amidine-based catalysts, particularly Cl-PIQ 2 and BTM 3, provides a convenient method for the kinetic resolution of these valuable compounds and often achieves excellent levels of enantioselectivity in this process. Density functional theory calculations indicate that the reaction occurs via N-acylation of the lactim tautomer and that cation-π interactions play a key role in the chiral recognition of lactam substrates.
- Yang, Xing,Bumbu, Valentina D.,Liu, Peng,Li, Ximin,Jiang, Hui,Uffman, Eric W.,Guo, Lei,Zhang, Wei,Jiang, Xuntian,Houk,Birman, Vladimir B.
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supporting information
p. 17605 - 17612
(2013/01/15)
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- Copper-catalyzed intramolecular C-H amination
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The amino-functionalization of tertiary, secondary and benzylic C-H bonds of tethered carbamates and sulfamates by iodosobenzene is catalyzed by Cu I-diimine complexes in moderate to good yield. Employing homochiral imine-Cucatalysts affords oxazolidinones and oxathiazinanes with modest enantioselectivity.
- Barman, Dipti N.,Nicholas, Kenneth M.
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supporting information; experimental part
p. 908 - 911
(2011/04/26)
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- Synthesis of α-CF3-substituted carbonyl compounds with relative and absolute stereocontrol using electrophilic CF3-transfer reagents
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Evans-type chiral lithium imide enolates undergo diastereoselective α-trifluoromethylation with a hypervalent iodine-CF3 reagent with up to 91% combined isolated yield and 97:3 dr. The resulting isolated diastereopure products can be further transformed into valuable products without racemization.
- Matousek, Vaclav,Togni, Antonio,Bizet, Vincent,Cahard, Dominique
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supporting information; experimental part
p. 5762 - 5765
(2012/01/06)
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- Catalysts for use in enantioselective synthesis
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Disclosed are compounds having the following formula: in which Z11 is selected from a substituted or unsubstituted saturated adamantyl or other polycyclic group and a substituted or unsubstituted branched acyclic group containing at least 5 carbon atoms at least one of which is a tertiary carbon; and in which Z12 is a cyclic imide. Methods of using these compounds as chiral catalysts for carbenoid reactions and for enantioselective C—H aminations are also described.
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Page/Page column 60; 65-66
(2008/12/05)
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- A silver-catalyzed intramolecular amidation of saturated C-H bonds
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Opportunities with silver: A dinuclear silver(I) compound was found to efficiently catalyze the intramolecular amidation of saturated C-H bonds of carbamates and sulfamates (see scheme). This highly regioselective, stereospecific reaction offers a practical method for the construction of cyclic nitrogen-containing organic molecules.
- Cui, Yong,He, Chuan
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p. 4210 - 4212
(2007/10/03)
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- Covalent modification of subtilisin Bacillus lentus Cysteine mutants with enantiomerically pure chiral auxiliaries causes remarkable changes in activity
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Methanethiosulfonate reagents may be used to introduce virtually unlimited structural modifications in enzymes via reaction with the thiol group of cysteine. The covalent coupling of enantiomerically pure (R) and (S) chiral auxiliary methanethiosulfonate ligands to cysteine mutants of subtilisin Bacillus lentus induces spectacular changes in catalytic activity between diastereomeric enzymes. Amidase and esterase kinetic assays using a low substrate approximation were used to establish k(cat)/K(M) values for the chemically modified mutants, and up to 3-fold differences in activity were found between diastereomeric enzymes. Changing the length of the carbon chain linking the phenyl or benzyl oxazolidinone ligand to the mutant N62C by a methylene unit reverses which diastereomeric enzyme is more active. Similarly, changing from a phenyl to benzyl oxazolidinone ligand at S166C reverses which diastereomeric enzyme is more active. Chiral modifications at S166C and L217C give CMMs having both high esterase k(cat)/K(M)'s and high esterase to amidase ratios with large differences between diastereomeric enzymes. Copyright (C) 2000 Elsevier Science Ltd.
- Dickman, Michael,Jones, J. Bryan
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p. 1957 - 1968
(2007/10/03)
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- A convenient enzymatic route to optically active 1-aminoindan-2-ol: Versatile ligands for HIV-1 protease inhibitors and asymmetric syntheses
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(1S,2R)- and (1R,2S)-1-aminoindan-2-ol were prepared in high enantiomeric excess (> 96%) by an immobilized lipase-catalyzed selective acylation of racemic trans-1-azidoindan-2-ol.
- Ghosh, Arun K.,Kincaid, John F.,Haske, Michael G.
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p. 541 - 544
(2007/10/03)
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- Highly diastereoselective dielsalder reaction mediated by a chiral auxiliary derived from amino indanol: The role of conformation on diastereoselectivity
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The oxazolidinone 2 derived from amino indanol 1 functions as a very efficient chiral auxiliary for the Diels-Alder reaction. The effect of conformation has been explored using a range of constrained phenyl glycinol analogues.
- Davies, Ian W.,Senanayake, Chris H.,Castonguayi, Laurie,Larsen, Robert D.,Verhoeven, Thomas R.,Reider, Paul J.
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p. 7619 - 7622
(2007/10/02)
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- Highly Enantioselective Aldol Reaction: Development of a New Chiral Auxiliary from cis-1-Amino-2-hydroxyindan
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Boron enolates obtained from optically active oxazolidinone derivative of cis-1-amino-2-hydroxyindan are reacted with various aldehydes to provide highly enantioselective aldol products in good yields.
- Ghosh, Arun K.,Duong, Tien T.,McKee, Sean P.
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p. 1673 - 1674
(2007/10/02)
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- Chemo-enzymatic synthesis of 1,2- and 1,3- amino-alcohols and their use in the enantioselective reduction of acetophenone and anti-acetophenone oxime methyl ether with borane
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New chiral amino-alcohols were enantioselectively synthesized using biotransformations as the key steps. They were used as ligand in the enantioselective borane reduction of acetophenone and of the corresponding anti oxime methyl ether.
- Didier, Eric,Loubinoux, Bernard,Ramos Tombo, Gerardo H.,Rihs, Grety
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p. 4941 - 4958
(2007/10/02)
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- Aminotellurinylation of Olefins and Its Utilization for Synthesis of 2-Oxazolidinones
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Benzenetellurinyl acetate or trifluoroacetate in combination with ethyl carbamate effected regio- and stereoselective aminotellurinylation of olefins in the presence of boron trifluoride etherate in chloroform under reflux to give ethyl carbamates in high yields.Benzenetellurinyl trifluoromethanesulfonate similarly did it even at the lower temperature of refluxing dichloromethane without Lewis acid.This reaction was successfully extended to cyclofunctionalization of olefinic carbamates into nitrogen heterocycles.Furthermore, when the aminotellurinylation was carried out in refluxing 1,2-dichloroethane, 2-oxazolidinone was obtained in a high yield.A mechanism of addition followed by intramolecular substitution in proposed on the basis of the stereochemistry of 2-oxazolidinone derivatives.
- Hu, Nan Xing,Aso, Yoshio,Otsubo, Tetsuo,Ogura, Fumio
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p. 4398 - 4404
(2007/10/02)
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