- Manganese-catalyzed homogeneous hydrogenation of ketones and conjugate reduction of α,β-unsaturated carboxylic acid derivatives: A chemoselective, robust, and phosphine-free in situ-protocol
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We communicate a user-friendly and glove-box-free catalytic protocol for the manganese-catalyzed hydrogenation of ketones and conjugated C[dbnd]C[sbnd]bonds of esters and nitriles. The respective catalyst is readily assembled in situ from the privileged [Mn(CO)5Br] precursor and cheap 2-picolylamine. The catalytic transformations were performed in the presence of t-BuOK whereby the corresponding hydrogenation products were obtained in good to excellent yields. The described system offers a brisk and atom-efficient access to both secondary alcohols and saturated esters avoiding the use of oxygen-sensitive and expensive phosphine-based ligands.
- Topf, Christoph,Vielhaber, Thomas
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- Group 6 Metal Carbonyl Complexes Supported by a Bidentate PN Ligand: Syntheses, Characterization, and Catalytic Hydrogenation Activity
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We report on the preparation of a series of phosphorus-nitrogen donor ligand complexes [M(CO)4(PN)], where M = Cr, Mo, W and PN is 2-(diphenylphosphino)ethylamine. The organometallic compounds were readily obtained upon reacting the respective metal hexacarbonyls with equimolar amounts of the pertinent ligand in the presence of tetraethylammonium bromide. The PN-ligated metal carbonyls were fully characterized by standard spectroscopic techniques and X-ray crystallography. The ability of the title compounds to function as homogeneous hydrogenation catalysts was probed in the reduction of acetophenone and benzaldehyde derivatives to yield the corresponding alcohols. The reaction setup was easily assembled by simply combining the components in the autoclave on the bench outside an inert-gas-operated glovebox system.
- Faust, Kirill,Topf, Christoph,Vielhaber, Thomas
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p. 4535 - 4543
(2020/12/23)
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- NBS-mediated synthesis of β-keto sulfones from benzyl alcohols and sodium arenesulfinates
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An efficient synthetic route towards the synthesis of β-keto sulfones has been developed from secondary benzyl alcohols using N-bromosuccinimide (NBS). The present protocol utilizes NBS as oxidant as well as brominating agent, readily accessible benzyl alcohols and sodium arenesulfinates as the sulfonylating reagent under mild conditions. The control experiments revealed that the reaction proceeds via oxidation of alcohol to ketone, α-bromination of ketone and nucleophilic substitution by sodium arenesulfinate. Furthermore, the efficiency of the methodology was tested with a gram scale reaction and also shown the synthetic utility.
- Muneeswara, Madithedu,Sundaravelu, Nallappan,Sekar, Govindasamy
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supporting information
p. 3479 - 3484
(2019/05/21)
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- Stereoselective amination of racemic sec-alcohols through sequential application of laccases and transaminases
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A one-pot/two-step bienzymatic asymmetric amination of secondary alcohols is disclosed. The approach is based on a sequential strategy involving the use of a laccase/TEMPO catalytic system for the oxidation of alcohols into ketone intermediates, and their following transformation into optically enriched amines by using transaminases. Individual optimizations of the oxidation and biotransamination reactions have been carried out, studying later their applicability in a concurrent process. Therefore, 17 racemic (hetero) aromatic sec-alcohols with different substitutions in the aromatic ring have been converted into enantioenriched amines with good to excellent selectivities (90-99% ee) and conversion values (67-99%). The scalability of the process was also demonstrated when two different amine donors were used in the transamination step, such as isopropylamine and cis-2-buten-1,4-diamine. Satisfyingly, both sacrificial amine donors can shift the equilibrium toward the amine formation, leading to the corresponding isolated enantioenriched amines with good to excellent results.
- Martínez-Montero, Lía,Gotor, Vicente,Gotor-Fernández, Vicente,Lavandera, Iván
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supporting information
p. 474 - 480
(2017/06/23)
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- Halogen-bonded iodonium ion catalysis: A route to α-hydroxy ketones: Via domino oxidations of secondary alcohols and aliphatic C-H bonds with high selectivity and control
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A domino synthesis of α-hydroxy ketones has been developed from benzylic secondary alcohols employing catalytic iodonium ions stabilized by DMSO. The reaction proceeds through an unprecedented sequential oxidation of alcohols to ketone and its α-hydroxylation in a controlled manner. The spectroscopic evidence establishes the possibility of formation of a stable halogen-bonded adduct between DMSO and iodonium ions.
- Guha, Somraj,Kazi, Imran,Mukherjee, Pranamita,Sekar, Govindasamy
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supporting information
p. 10942 - 10945
(2017/10/13)
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- A versatile and one-pot strategy to synthesize ?±-amino ketones from benzylic secondary alcohols using N -bromosuccinimide
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A metal-free one-pot strategy has been developed for the first time to synthesize pharmaceutically important ?±-amino ketones from readily available benzylic secondary alcohols and amines using N-bromosuccinimide. This new reaction proceeds via three consecutive steps involving oxidation of alcohols, ?±-bromination of ketones, and nucleophilic substitution of ?±-bromo ketones to give ?±-amino ketones. Importantly, this novel one-pot greener reaction avoids direct usage of toxic and corrosive bromine. This methodology has been employed efficiently to synthesize pharmaceutically important amfepramone and pyrovalerone in a single step.
- Guha, Somraj,Rajeshkumar, Venkatachalam,Kotha, Surya Srinivas,Sekar, Govindasamy
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supporting information
p. 406 - 409
(2015/03/04)
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- Controlled alcohol-carbonyl interconversion by nickel catalysis
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All in one pot: A general synthetic platform allows the interconversion of alcohols and carbonyl compounds in a predictable and controlled fashion in one pot. Under the action of a Ni catalyst, PhCl, CsF, and arylboronates, several multistep alcohol-carbonyl interconversions have been achieved with good overall efficiency (see scheme). A one-pot nickel-catalyzed synthesis of flumecinol (a hepatic microsomal enzyme inducer) has also been demonstrated. Copyright
- Maekawa, Takehisa,Sekizawa, Hiromi,Itami, Kenichiro
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p. 7022 - 7026
(2011/09/30)
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- N, N′-dioxide-Cu(OTf)2 complex catalyzed highly enantioselective amination reaction of N-acetyl enamide
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The N,N′-dioxide-Cu(OTf)2 complexes were applied in the asymmetric amination reaction of N-acetyl enamides with dialkyl azodicarboxylate, giving the corresponding products in good yields with high enantioselectivities (up to 91% ee). Precursors of vicinal diamine were readily obtained with excellent diastereoselectivities (>95:5) by NaBH4 reduction.
- Chang, Lu,Kuang, Yulong,Qin, Bo,Zhou, Xin,Liu, Xiaohua,Lin, Lili,Feng, Xiaoming
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supporting information; experimental part
p. 2214 - 2217
(2010/08/06)
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- Pharmaceutical agents that impede the initiation and progression of primary and secondary DMS disruptions
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Compositions comprising a pharmaceutically effective amount of a compound that impedes disruption of intact dense microspheres (DMS) by acting on DMS either to prevent disruption, or if disrupted, act on pre-disrupted DMS in such a way that, when the comp
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- Synthesis and activity of 2-methyl-3-aminopropiophenones as centrally acting muscle relaxants
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Some novel 2-methyl-3-aminopropiophenones were synthesized and their centrally acting muscle relaxant activities were,evaluated for an inhibitory effect on the flexor reflex in rats. The structure-activity relationships are discussed. In this series 2-methyl-3-pyrrolidino-1-(4-trifluoromethylphenyl)-propan-1-one (28) showed significant centrally acting muscle relaxant activity. In addition, the activities of each enantiomer (28-(S) and (R)) were studied along with their acute toxicities. Compound 28-(R) was found to exhibit more potent activity and weaker acute toxicity than 28-(S). Accordingly, compound 28-(R) (NK433) is under development as a novel centrally acting muscle relaxant.
- Shiozawa,Narita,Izumi,Kurashige,Sakitama,Ishikawa
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- Asymmetric syntheses of (S)-Fenfluramine using Sharpless Epoxidation Methods
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We describe one synthesis of (S)-fenfluramine and several syntheses of its precursors (R)- and (S)-1-(meta-trifluoromethylphenyl)propan-2-ols.They were obtained from the asymmetric epoxidation of the primary allylic alcohol 5 and from the kinetic resolution with asymmetric epoxidation of teh secondary allylic alcohol 6.
- Goument, Bertrand,Duhamel, Lucette,Mauge, Robert
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p. 171 - 188
(2007/10/02)
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- Epoxides, amino alcohols, and aziridines as key intermediates in the asymmetric synthesis of (S)-fenfluramine
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The epoxides 3E, 3Z and 8 were obtained from the isomeric alkenes 2E, 2Z and 7.The epoxides were ring-opened by ethylamine in ethanol yielding mixtures of the amino alcohols 4E and 11E, 4T and 11T, and 9, respectively, which were transformed into the aziridines 5trans, 5cis and 12.The regiospecific Pd/C-catalyzed reduction of these aziridines gave fenfluramine 1.The three epoxides 3trans, 3cis and 8 were reduced regiospecifically into 1-propan-2-ol 6, a potent precursor to fenfluramine 1.The validity of our method for asymmettric synthesis has been demonstrated by a synthesis of (S)-fenfluramine 1 starting from the amino alcohol (S)-9.Keyword - fenfluramine / asymmetric synthesis / epoxide / amino alcohol / aziridine / regiospecific catalytic hydrogenation / 1-propan-2-ols
- Goument, B.,Duhamel, L.,Mauge, R.
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p. 459 - 466
(2007/10/02)
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