- Deactivation mechanisms of iodo-iridium catalysts in chiral amine racemization
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The homogenous, [IrCp?I2]2, SCRAM catalyst (1) is active in the racemization of chiral amines. NMR, kinetic and structural mechanistic studies have determined the cause of catalyst deactivation to occur when ammonia or methylamine are liberated by hydrolysis or aminolysis of the intermediate imine, which tightly coordinate to the iridium centre to block turnover. Control of moisture and substrate concentration can suppress deactivation, whilst partial reactivation of spent catalyst was identified using hydroiodic acid.
- Kwan, Maria H.T.,Pokar, Nisha P.B.,Good, Catherine,Jones, Martin F.,Munday, Rachel,Screen, Thomas,Blacker, A. John
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supporting information
(2020/12/29)
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- Continuous Flow Chiral Amine Racemization Applied to Continuously Recirculating Dynamic Diastereomeric Crystallizations
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A new, dynamic diastereomeric crystallization method has been developed, in which the mother liquors are continuously separated, racemized over a fixed-bed catalyst, and recirculated to the crystallizer in a resolution-racemization-recycle (R3) process. S
- Kwan, Maria H. T.,Breen, Jessica,Bowden, Martin,Conway, Louis,Crossley, Ben,Jones, Martin F.,Munday, Rachel,Pokar, Nisha P. B.,Screen, Thomas,Blacker, A. John
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p. 2458 - 2473
(2021/02/06)
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- CHIRALITY SENSING WITH MOLECULAR CLICK CHEMISTRY PROBES
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The present invention relates to an analytical method that includes providing a sample potentially containing a chiral analyte that can exist in stereoisomeric forms, and providing a probe selected from the group consisting of coumarin-derived Michael acceptors, dinitrofluoroarenes and analogs thereof, arylsulfonyl chlorides and analogs thereof, arylchlorophosphines and analogs thereof, aryl halophosphites, and halodiazaphosphites. The sample is contacted with the probe under conditions to permit covalent binding of the probe to the analyte, if present in the sample; and, based on any binding that occurs, the absolute configuration of the analyte in the sample, and/or the concentration of the analyte in the sample, and/or the enantiomeric composition of the analyte in the sample is/are determined. The probe may be a coumarin-derived Michael acceptor, a di nitrofluoroarene or analog thereof, an arylsulfonyl chloride or analog thereof, an arylchlorophosphine or analog thereof, an aryl halophosphite, or a halodiazaphosphite.
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-
Paragraph 0280; 0284
(2020/02/23)
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- Photocatalytic Difunctionalization of Vinyl Ureas by Radical Addition Polar Truce–Smiles Rearrangement Cascades
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We report tandem alkyl-arylations and phosphonyl-arylations of vinyl ureas by way of a photocatalytic radical-polar crossover mechanism. Addition of photoredox-generated radicals to the alkene forms a new C?C or C?P bond and generates a product radical adjacent to the urea function. Reductive termination of the photocatalytic cycle generates an anion that undergoes a polar Truce–Smiles rearrangement, forming a C?C bond. The reaction is successful with a range of α-fluorinated alkyl sodium sulfinate salts and diarylphosphine oxides as radical precursors, and the conformationally accelerated Truce–Smiles rearrangement is not restricted by the electronic nature of the migrating aromatic ring. Formally the reaction constitutes an α,β-difuctionalisation of a carbon–carbon double bond, and proceeds under mild conditions with visible light and a readily available organic photocatalyst. The products are α,α-diaryl alkylureas typically functionalized with F or P substituents that may be readily converted into α,α-diaryl alkylamines.
- Abrams, Roman,Clayden, Jonathan
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supporting information
p. 11600 - 11606
(2020/05/25)
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- Tackling N-Alkyl Imines with 3d Metal Catalysis: Highly Enantioselective Iron-Catalyzed Synthesis of α-Chiral Amines
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A readily activated iron alkyl precatalyst effectively catalyzes the highly enantioselective hydroboration of N-alkyl imines. Employing a chiral bis(oxazolinylmethylidene)isoindoline pincer ligand, the asymmetric reduction of various acyclic N-alkyl imines provided the corresponding α-chiral amines in excellent yields and with up to >99 % ee. The applicability of this base metal catalytic system was further demonstrated with the synthesis of the pharmaceuticals Fendiline and Tecalcet.
- Blasius, Clemens K.,Gade, Lutz H.,Heinrich, Niklas F.,Vasilenko, Vladislav
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supporting information
p. 15974 - 15977
(2020/07/04)
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- Cooperative Lewis Acid/Cp?CoIII Catalyzed C-H Bond Activation for the Synthesis of Isoquinolin-3-ones
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A facile route toward the synthesis of isoquinolin-3-ones through a cooperative B(C6F5)3- and Cp?CoIII-catalyzed C-H bond activation of imines with diazo compounds is presented. The inclusion of a catalytic amount of B(C6F5)3 results in a highly efficient reaction, thus enabling unstable NH imines to serve as substrates. CoIII-operative catalysis: The first facile route toward the synthesis of isoquinolin-3-ones through cooperative C-H bond activation with B(C6F5)3 (BCF in picture) and Cp?CoIII (Cp?=C5Me5) is presented. The newly developed catalytic system is highly reactive, thus unstable NH imines can serve as substrates.
- Kim, Ju Hyun,Gre?ies, Steffen,Glorius, Frank
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supporting information
p. 5577 - 5581
(2016/05/09)
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- Iron catalysed nitrosation of olefins to oximes
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Fe(BF4)2·6H2O/2,6- pyridinedicarboxylic acid catalysed nitrosation of a wide variety of substituted styrenes has been developed in the presence of t-BuONO/NaBH4 under H2 pressure (10 bar) in MeOH-H2O (5 : 1) to afford corresponding oximes in good to excellent yields.
- Ray, Ritwika,Chowdhury, Abhishek Dutta,Maiti, Debabrata,Lahiri, Goutam Kumar
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supporting information
p. 38 - 41
(2014/01/06)
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- Characterization of three novel enzymes with imine reductase activity
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Imine reductases (IRED) are promising catalysts for the synthesis of optically pure secondary cyclic amines. Three novel IREDs from Paenibacillus elgii B69, Streptomyces ipomoeae 91-03 and Pseudomonas putida KT2440 were identified by amino acid or structural similarity search, cloned and recombinantly expressed in E. coli and their substrate scope was investigated. Besides the acceptance of cyclic amines, also acyclic amines could be identified as substrates for all IREDs. For the IRED from P. putida, a crystal structure (PDB-code 3L6D) is available in the database, but the function of the protein was not investigated so far. This enzyme showed the highest apparent E-value of approximately Eapp = 52 for (R)-methylpyrrolidine of the IREDs investigated in this study. Thus, an excellent enantiomeric purity of >99% and 97% conversion was reached in a biocatalytic reaction using resting cells after 24 h. Interestingly, a histidine residue could be confirmed as a catalytic residue by mutagenesis, but the residue is placed one turn aside compared to the formally known position of the catalytic Asp187 of Streptomyces kanamyceticus IRED.
- Gand,Müller,Wardenga,H?hne
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p. 126 - 132
(2015/02/19)
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- Amines bearing tertiary substituents by tandem enantioselective carbolithiation-rearrangement of vinylureas
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In the presence of (-)-sparteine or a (+)-sparteine surrogate, organolithiums add to N-alkenyl-N'-arylureas to give benzylic organolithiums in an enantioselective manner. Under the influence of DMPU, these organolithiums undergo rearrangement with migrati
- Tait, Michael,Donnard, Morgan,Minassi, Alberto,Lefranc, Julien,Bechi, Beatrice,Carbone, Giorgio,O'Brien, Peter,Clayden, Jonathan
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supporting information
p. 34 - 37
(2013/03/28)
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- Alkyloximes and imines via silyl carbamates
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The reactions between different N,O-bis-trimethylsilyl-carbamates and oxo compounds were studied. The N,O-bis-trimethylsilyl-N-methoxy-carbamate converts ketones to the corresponding O-methyl oximes. The product is usually a mixture of syn and anti isomers. If the carbonyl compound bears a hydroxyl group, the oxime formation and the O-silylation take place simultaneously. In the case of -haloketones, the undesired substitution of halogen was not observed. The reactions between N,O-bis-trimethylsilyl-N-methyl-carbamate and oxo compounds resulted in the corresponding imines, although the yield are moderate in some cases. Analoguos reaction of ferrocenylated oxo derivatives gave similar results.
- Kardon, Ferenc,Moertl, Maria,Csampai, Antal,Ujszaszy, Kalman,Knausz, Dezso
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experimental part
p. 914 - 924
(2011/04/23)
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- Geometry-selective synthesis of e or Z N -vinyl ureas (N -carbamoyl enamines)
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N-Vinyl ureas are emerging as a valuable class of compounds with both nucleophilic and electrophilic reactivity. They may be made by capturing the enamine tautomer of an imine with an isocyanate, a reaction which in general leads to the E isomer of the vi
- Lefranc, Julien,Tetlow, Daniel J.,Donnard, Morgan,Minassi, Alberto,Galvez, Erik,Clayden, Jonathan
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supporting information; experimental part
p. 296 - 299
(2011/03/22)
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- Tandem β-alkylation-α-arylation of amines by carbolithiation and rearrangement of N -carbamoyl enamines (Vinyl Ureas)
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Organolithiums add in an umpolung fashion to the β-carbon of N-carbamoyl enamines (N-vinyl ureas). The reaction proceeds with syn diastereospecificity and provides urea-stabilized, configurationally defined organolithiums. Facilitated by coordinating solv
- Clayden, Jonathan,Donnard, Morgan,Lefranc, Julien,Minassi, Alberto,Tetlow, Daniel J.
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supporting information; experimental part
p. 6624 - 6625
(2010/07/03)
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- Simplified ketimine preparation
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An extremely simple method for preparing imines from aryl and alkylaryl ketones and a variety of amines is presented. The process involves the diffusion of the appropriate amine vapor from one arm of an H-tube into the other arm containing the ketone. Most reactions are quantitative, and, in many cases, there is no real work-up or purification required.
- Thienthong, Neeranat,Bergman, Ylva E.,Perlmutter, Patrick
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experimental part
p. 2683 - 2693
(2009/12/06)
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- On the mechanism of conversion of 4-carboxy-3,4-dihydro-3-phenyl-1(2H)-isoquinolones to indeno[1,2-c]isoquinolines by thionyl chloride
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It has been known for a long time that thionyl chloride can effectively mediate the transformation of 4-carboxy-3,4-dihydro-3-phenyl-1(2H)-isoquinolones to indeno[1,2-c]isoquinolines. The mechanism of this unique transformation, however, remains to be established. Evidence is presented to demonstrate that (1) the two-electron dehydrogenation precedes Friedel-Crafts cyclization and (2) the two-electron dehydrogenation occurs via H-4 deprotonation and subsequent O-sulfinylation of the lactam moiety instead of C-sulfinylation of the carbon α to the carboxyl group.
- Xiao, Xiangshu,Morrell, Andrew,Fanwick, Phillip E.,Cushman, Mark
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p. 9705 - 9712
(2007/10/03)
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- Regiochemistry in aryl radical cyclisations (5-exo versus 6-endo) of N-vinylic 2-iodobenzamides
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Bu3SnH-mediated aryl radical cyclisations of a range of N-vinylic 2-iodobenzamides 10 were examined. The enamides 10a-d gave exclusively the 5-exo cyclisation products 11a-d, whereas the enamides 10e,f having a phenyl substituent on the vinylic carbon ato
- Ishibashi, Hiroyuki,Ohata, Kohei,Niihara, Michiyo,Sato, Tatsunori,Ikeda, Masazumi
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p. 547 - 554
(2007/10/03)
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- Synthesis of pyrrolidin-2-ones by 5-endo-trigonal radical cyclisation of N-vinyl-2,2-bis(phenylsulfanyl)acetamides
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A series of N-methyl-N-(1-substituted or 1,2-disubstituted vinyl)-2,2-bis(phenylsulfanyl)acetamides, upon treatment with tributyltin hydride in the presence of a catalytic amount of AIBN in boiling toluene, underwent smooth cyclisation in a 5-endo-trig ma
- sato, Tatsunori,Chono, Noriko,Ishibashi, Hiroyuki,Ikeda, Masazumi
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p. 1115 - 1120
(2007/10/02)
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- Synthesis of 3-Phenylisoquinolones by Reaction of Simple Pyrroline-2,3-diones with Benzyne. New Mechanistic Considerations
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3-Phenylisoquinolones were obtained by cycloaddition of benzyne to 5-phenylpyrroline-2,3-diones.New mechanistic hypotheses for these transformations are discussed.
- Cobas, Agustin,Guitian, Enrique,Castedo, Luis
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p. 3113 - 3117
(2007/10/02)
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- Reactions of N-Halo-N-methylbenzylamines with MeONa-MeOH and t-BuOK-t-BuOH. Effects of β-Carbon Substituent and Base-Solvent System upon the Imine-Forming Transition State
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Elimination reactions of YC6H4CH(R)N(X)CH3 in which R = Me and Ph and X = Cl and Br promoted by MeONa-MeOH and t-BuOK-t-BuOH have been studied kinetically.The elimination reactions are regiospecific, producing only the corresponding N-benzylidenemethylami
- Bartsch, Richard A.,Cho, Bong Rae
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p. 2252 - 2257
(2007/10/02)
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- Thermolyse et photolyse de tetrazolines
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The thermolysis of tetrazolines leads to diaziridines the cyclic carbon atom bears two hydrogens or one hydrogen and a methyl group.If one of the substituents of this carbon is aromatic, two cycloreversions may be observed, giving azides and imines.The photolysis at low temperature leads to diaziridines, except when the cyclic carbon atom bears two insaturated substituents.
- Carboni, B.,Tonnard, F.,Carrie, R.
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p. 525 - 530
(2007/10/02)
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- Unusual Acid-Catalyzed Rearrangement of Two α,α'-Diimino-oximes
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2-pyrrolidines (vinamidines, 3-6) were obtained either via activation of the corresponding vinilogous amide 1 with Meerwein salt and subsequent treatment of the intermediate 2 with an amine, or more directly by acid-cata
- Fuhrer, Walter,Rasetti, Vittorio,Rihs, Grety
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p. 1235 - 1242
(2007/10/02)
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- Photolysis of Alkyl Azides. Evidence for a Nonnitrene Mechanism
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The photolyses of nine sec- and tert-alkyl azides have been studied in detail.The products consist of imines derived from 1,2-shifts of groups on the alkyl carbon atom α to the azide nitrogen atom.No evidence of typical nitrene processes (aromatic substitution, aliphatic C-H insertion) was found.The imine product distributions are rationalized on the basis of a preferred migration orientation in the photochemically excited azide, along with a consideration of either ground or excited state rotational equilibration of the azide.Photolyses of selected azides carried out over an approximately 200 deg C temperature range allow an estimation of apparent activation energy differences between different group migrations.These energy differences are in the range of 70-493 cal/mol and are related to rotational equilibration of the alkyl azide.
- Kyba, Evan P.,Abramovitch, Rudolph A.
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p. 735 - 740
(2007/10/02)
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