- Air and water stable secondary phosphine oxides as diazaphospholene precatalysts
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Air-stable secondary phosphine oxides (SPOs) are readily formed from diazaphospholene bromides. In the presence of pinacolborane, these SPOs are transformed into catalytically active diazaphospholene hydrides. A silyl triflate transforms the SPOs into pho
- Lundrigan, Travis,Tien, Chieh-Hung,Robertson, Katherine N.,Speed, Alexander W. H.
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- High-Throughput Screening of Reductive Amination Reactions Using Desorption Electrospray Ionization Mass Spectrometry
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This study describes the latest generation of a high-throughput screening system that is capable of screening thousands of organic reactions in a single day. This system combines a liquid handling robot with desorption electrospray ionization (DESI) mass spectrometry (MS) for a rapid reaction mixture preparation, accelerated synthesis, and automated MS analysis. A total of 3840 unique reductive amination reactions were screened to demonstrate the throughputs that are capable with the system. Products, byproducts, and intermediates were all monitored in full-scan mass spectra, generating a complete view of the reaction progress. Tandem mass spectrometry experiments were conducted to verify the identity of the products formed. The amine and electrophile reactivity trends represented in the data match what is expected from theory, indicating that the system accurately models the reaction performance. The DESI results correlated well with those generated using more traditional mass spectrometry techniques like liquid chromatography-mass spectrometry, validating the data generated by the system.
- Cooks, R. Graham,Ferreira, Christina R.,Li, Yangjie,Logsdon, David L.,Paschoal Sobreira, Tiago Jose,Thompson, David H.
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supporting information
p. 1647 - 1657
(2020/10/26)
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- Hydroboration Catalyzed by 1,2,4,3-Triazaphospholenes
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The synthesis and study of the catalytic activity of 1,2,4,3-triazaphospholenes (TAPs) is reported. TAPs represent a more modular scaffold than previously reported diazaphospholenes. TAP halides were shown to catalyze the 1,2 hydroboration of 19 imines, and three α,β unsaturated aldehydes with pinacolborane, including examples that did not undergo hydroboration by previously reported diazaphospholene systems. DFT calculations support a mechanism where a triazaphospholene cation interacts with the substrate, a mechanism distinct from diazaphospholene catalyzed hydroborations.
- Tien, Chieh-Hung,Adams, Matt R.,Ferguson, Michael J.,Johnson, Erin R.,Speed, Alexander W. H.
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supporting information
p. 5565 - 5568
(2017/10/25)
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- A stereoselective, catalytic strategy for the in-flow synthesis of advanced precursors of rasagiline and tamsulosin
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The diastereoselective, trichlorosilane-mediate reduction of imines, bearing different and removable chiral auxiliaries, in combination either with achiral bases or catalytic amounts of chiral Lewis bases, was investigated to afford immediate precursors of chiral APIs (Active Pharmaceutical Ingredients). The carbon-nitrogen double bond reduction was successfully performed in batch and in flow mode, in high yields and almost complete stereocontrol. By this metal-free approach, the formal synthesis of rasagiline and tamsulosin was successfully accomplished in micro(meso) flow reactors, under continuous flow conditions. The results of these explorative studies represent a new, important step towards the development of automated processes for the preparation of enantiopure biologically active compounds.
- Brenna, Davide,Pirola, Margherita,Raimondi, Laura,Burke, Anthony J.,Benaglia, Maurizio
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p. 6242 - 6247
(2017/09/30)
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- Asymmetric Imine Hydroboration Catalyzed by Chiral Diazaphospholenes
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The first use of diazaphospholenes as chiral catalysts has been demonstrated with enantioselective imine hydroboration. A chiral diazaphospholene prepared in a simple three-step synthesis from commercial materials has been shown to achieve the highest enantioselectivity for the hydroboration of alkyl imines with pinacolborane reported to date. Enantiomer ratios of up to 88:12 were obtained with low (2 mol %) catalyst loadings. Twenty examples of asymmetric reduction employing this main-group catalysis protocol, including the synthesis of the pharmaceuticals ent-rasagiline and fendiline, are shown.
- Adams, Matt R.,Tien, Chieh-Hung,McDonald, Robert,Speed, Alexander W. H.
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p. 16660 - 16663
(2017/12/13)
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- Diazaphospholene Precatalysts for Imine and Conjugate Reductions
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The first examples of 1,3,2-diazaphospholene-catalyzed imine reduction and conjugate reduction reactions are reported. This approach employs readily synthesized alkoxydiazaphospholene precatalysts that can be handled in open air. Reduction of substrates containing Lewis basic functionality, isolated unsaturation, and protic functional groups was accomplished. The synthetic utility of this approach is demonstrated by the synthesis of the important antiparkinson medicine rasagiline and the natural product zingerone.
- Adams, Matt R.,Tien, Chieh-Hung,Huchenski, Blake S. N.,Ferguson, Michael J.,Speed, Alexander W. H.
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supporting information
p. 6268 - 6271
(2017/05/19)
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- METHOD FOR PRODUCING NOVEL ORGANOMETALLIC COMPLEX AND AMINE COMPOUND
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The purpose of the invention is to provide a novel organometallic compound that can be utilized as a catalyst having high generality, high activity, and excellent functional group selectivity. The invention pertains to a novel organometallic compound represented by general formula (1) that catalyzes a reductive amination reaction.
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Paragraph 0218
(2016/03/19)
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- Synthesis and catalytic reactivity of bis(amino)cyclopropenylidene carbene-borane adducts
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The first reported neutral boron(III) adducts of bis(amino)cyclopropenylidene carbenes (BAC carbenes) have been synthesized, structurally characterized, and applied in homogeneous reaction chemistry. These air-stable adducts have been prepared by the combination of a BAC carbene lithium tetrafluoroborate adduct with borane dimethyl sulfide, boron trifluoride etherate, or dicyclohexylborane. A borenium cation derived in situ from the dicyclohexylborane adduct catalytically reduces unhindered benzyl ketimines, a class of substrate that cannot be reduced by prior borenium catalysts, at room temperature, employing 20 atm of hydrogen gas as the terminal reductant.
- Huchenski, Blake S. N.,Adams, Matt R.,McDonald, Robert,Ferguson, Michael J.,Speed, Alexander W. H.
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p. 3101 - 3104
(2016/10/09)
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- Rhodium-catalyzed intermolecular C-H amination of simple hydrocarbons using the shelf-stable nonafluorobutanesulfonyl azide
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A new procedure has been developed for the direct intermolecular C-H amination of simple hydrocarbons using shelf-stable nonafluorobutanesulfonyl azide in the presence of a dirhodium(ii) tetracarboxylate catalyst under mild reaction conditions. Some mechanistic details are briefly discussed on the basis of control experiments.
- Suarez, Jose Ramon,Chiara, Jose Luis
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p. 9194 - 9196
(2013/09/24)
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- Asymmetric hydrogenation of N-alkyl and N-aryl ketimines using chiral cationic Ru(diamine) complexes as catalysts: The counteranion and solvent effects, and substrate scope
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Asymmetric hydrogenation of N-alkyl and N-aryl ketimines catalyzed by chiral cationic η6-arene-(N-monosulfonylated diamine) Ru(II) complexes has been investigated. Strong counteranion and solvent effects on the enantioselectivity were observed. The ruthenium catalyst bearing non-coordinating BArF- anion was found to be particularly effective for the hydrogenation of acyclic and exocyclic N-alkyl ketimines in the presence of (Boc)2O in dichloromethane or even under solvent-free conditions, providing chiral amines with up to >99% ee and full conversions. Alternatively, the ruthenium catalyst bearing achiral phosphate anion together with corresponding phosphoric acid as the additive was also efficient for the hydrogenation of N-alkyl ketimines in the absence of (Boc)2O with excellent enantioselectivities and full conversions. For N-aryl ketimines lower enantiomeric excesses were observed by using the ruthenium catalyst bearing BArF- anion. This catalytic protocol thus provides a facile and practical access to optically active amines and has been successfully employed in the gram-scale synthesis of enantiomerically pure (+)-sertraline.
- Chen, Fei,Ding, Ziyuan,He, Yanmei,Qin, Jie,Wang, Tianli,Fan, Qing-Hua
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p. 5248 - 5257
(2012/08/08)
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- Secondary amine formation from reductive amination of carbonyl compounds promoted by lewis acid using the InCl3ZEt3SiH system
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A robust and reliable method has been developed for reductive amination of primary amines with various aldehydes and ketones using Zn(ClO4) 2.6H20 as a catalyst. [In-H] generated in situ via a combination of InCl3 and Et3SiH is employed as an effective reducing system. A variety of secondary amines can be synthesized in a one-pot procedure in excellent yields.
- Lee, On-Yi,Law, Ka-Lun,Yang, Dan
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supporting information; experimental part
p. 3302 - 3305
(2009/11/30)
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- Pd(OAc)2-catalyzed carbonylation of amines
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A phosphine-free catalytic system [Pd(OAc)2-Cu(OAc) 2-air] induced a substrate-specific carbonylation of amines in boiling toluene under CO gas (1 atm). Symmetrical N,N′-dialkylureas were obtained by the carbonylation of primary amines. N,N,N′-Trialkylureas were selectively formed by addition of a secondary amine to the above reaction vessel. Secondary amines did not give tetraalkylureas. However, dialkylamines with a phenyl group on their alkyl chains, such as N-monoalkylated benzylic amine or phenethylamine derivatives, underwent a direct aromatic carbonylation to afford five- or six-membered benzolactams. In the carbonylation, the chelation effect or steric repulsion between Pd(II) and the meta-substituent in the ortho-palladation and the ring sizes of cyclopalladation products that were formed prior to carbonylation were found to generate good site selectivity and increase the reaction rate. In contrast, carbonylation of ω- arylalkylamines with a hydroxyl group gave neither ureas nor benzolactams but instead produced 1,3-oxazolidinones smoothly. Hydrochlorides of amines also underwent carbonylation to afford the corresponding amides under the conditions used. This procedure made it possible to prepare ureas of amino acid esters and N-alkylcarbamates in practical yields.
- Orito, Kazuhiko,Miyazawa, Mamoru,Nakamura, Takatoshi,Horibata, Akiyoshi,Ushito, Harumi,Nagasaki, Hideo,Yuguchi, Motoki,Yamashita, Satoshi,Yamazaki, Tetsuro,Tokuda, Masao
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p. 5951 - 5958
(2007/10/03)
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- Imine hydrosilylation, uses and reagents related thereto
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The method of the present invention provides a simple general route to a wide range of secondary amines.
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- B(C6F5)3-catalyzed Hydrosilation of Imines via Silyliminium Intermediates
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formula presented A broad range of benzaldimines and ketimines can be hydrosilated efficiently, employing B(C6F5)3 as a catalyst in conjunction with PhMe2SiH. Spectral evidence supports the intermediacy of a silyliminium cation with a hydridoborate counterion formed via abstraction of a hydride from PhMe2SiH by B(C6F5)3 in the presence of imines.
- Blackwell, James M.,Sonmor, Eric R.,Scoccitti, Tiziana,Piers, Warren E.
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p. 3921 - 3923
(2007/10/03)
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- Method for preparing optically active 1-aminoindan derivatives
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Novel derivatives of 1-aminoindan and their salts are described. Optically active 1-aminoindan derivatives are prepared by reacting a N-benzyl analog of the desired compound with an enantiomer of mandelic acid. Parkinson's disease, dementia, epilepsy, con
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- Free-Radical Chemistry of Imines
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Aryl radicals bearing an aldimino functional group as part of an ortho substituent cyclized by addition to C and/or N of the imino group.When the choice was between 5-exo closure to C and 6-endo closure to N, the former predominated.However, 6-endo closure to C predominated over 5-exo cyclization to N in isomeric imines.Absolute values of cyclization rate constants were determined and an explanation for the unusual 6-endo preference is offered.Chiral induction in 6-endo cyclization to C of an aldimine from D-glyceraldehyde acetonide was observed, and its sense was determined.
- Tomaszewski, Miroslaw J.,Warkentin, John,Werstiuk, Nick H.
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p. 291 - 322
(2007/10/02)
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- Chiral Induction in Aryl Radical Cyclization to the Aldimino Functional Group
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6-endo Cyclization of aryl radicals to carbon of aldimino double bonds (N-5/C-6) in chiral ortho-substituents afforded 1,2,3,4-tetrahydroisoquinolines in yields to 69percent, with 58percent d.e. and 97percent e.e., while 5-exo cyclization to carbon in isomeric radicals (C-5/N-6 aldimine), leading to indanamines, was highly regioselective and fast, k5-exo = 3.9 * 108 s-1 at 80 deg C.
- Tomaszewski, Miroslaw J.,Warkentin, John
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p. 966 - 968
(2007/10/02)
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