- One-Pot Deoxygenation and Substitution of Alcohols Mediated by Sulfuryl Fluoride
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Sulfuryl fluoride is a valuable reagent for the one-pot activation and derivatization of aliphatic alcohols, but the highly reactive alkyl fluorosulfate intermediates limit both the types of reactions that can be accessed as well as the scope. Herein, we report the SO2F2-mediated alcohol substitution and deoxygenation method that relies on the conversion of fluorosulfates to alkyl halide intermediates. This strategy allows the expansion of SO2F2-mediated one-pot processes to include radical reactions, where the alkyl halides can also be exploited in the one-pot deoxygenation of primary alcohols under mild conditions (52-95% yield). This strategy can also enhance the scope of substitutions to nucleophiles that are previously incompatible with one-pot SO2F2-mediated alcohol activation and enables substitution of primary and secondary alcohols in 54-95% yield. Chiral secondary alcohols undergo a highly stereospecific (90-98% ee) double nucleophilic displacement with an overall retention of configuration.
- Epifanov, Maxim,Mo, Jia Yi,Dubois, Rudy,Yu, Hao,Sammis, Glenn M.
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supporting information
p. 3768 - 3777
(2021/03/01)
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- In Situ Generated Gold Nanoparticles on Active Carbon as Reusable Highly Efficient Catalysts for a Csp3 ?Csp3 Stille Coupling
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Gold nanoparticle catalysts are important in many industrial production processes. Nevertheless, for traditional Csp2-Csp2 cross-coupling reactions they have been rarely used and Pd catalysts usually give a superior performance. Herein we report that in situ formed gold metal nanoparticles are highly active catalysts for the cross coupling of allylstannanes and activated alkylbromides to form Csp3-Csp3 bonds. Turnover numbers up to 29 000 could be achieved in the presence of active carbon as solid support, which allowed for convenient catalyst recovery and reuse. The present study is a rare case where a gold metal catalyst is superior to Pd catalysts in a cross-coupling reaction of an organic halide and an organometallic reagent.
- Holz, Julia,Pfeffer, Camilla,Zuo, Hualiang,Beierlein, Dennis,Richter, Gunther,Klemm, Elias,Peters, René
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supporting information
p. 10330 - 10334
(2019/06/27)
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- Promotion of Appel-type reactions by N-heterocyclic carbenes
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N-Heterocyclic carbenes (NHCs) have been extensively used as a versatile class of catalysts and ligands in organocatalytic and organometallic chemistry. However, there are only a small number of synthetic applications where they act as reagents. Here we demonstrate that NHCs can be used as stoichiometric redox reagents for Appel-type halogenation reactions of alcohols. This new reactivity reveals a fresh and interesting aspect and enriches the chemistry of NHCs in an underexplored area. The potential of performing this chemical transformation at the catalytic level using an NHC-oxide derivative is also investigated.
- Hussein, Mohanad A.,Nguyen, Thanh Vinh
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supporting information
p. 7962 - 7965
(2019/07/12)
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- Transition-Metal-Free Stereospecific Cross-Coupling with Alkenylboronic Acids as Nucleophiles
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We herein report a transition-metal-free cross-coupling between secondary alkyl halides/mesylates and aryl/alkenylboronic acid, providing expedited access to a series of nonchiral/chiral coupling products in moderate to good yields. Stereospecific SN2-type coupling is developed for the first time with alkenylboronic acids as pure nucleophiles, offering an attractive alternative to the stereospecific transition-metal-catalyzed C(sp2)-C(sp3) cross-coupling.
- Li, Chengxi,Zhang, Yuanyuan,Sun, Qi,Gu, Tongnian,Peng, Henian,Tang, Wenjun
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p. 10774 - 10777
(2016/09/09)
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- Cosolvent-Promoted O-Benzylation with Silver(I) Oxide: Synthesis of 1′-Benzylated Sucrose Derivatives, Mechanistic Studies, and Scope Investigation
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A cosolvent-promoted O-benzylation strategy with Ag2O was developed. The cosolvent consisting of CH2Cl2 and n-hexane can not only improve the reaction solubility for carbohydrates but also increase the benzylation efficiency. The formation of byproducts is greatly inhibited in the developed method. This method is simple, mild, and highly effective, and numerous 1′-benzylated sucrose derivatives were prepared including a photoreactive (trifluoromethyl)phenyldiazirine-based sucrose. The mechanisms of benzylation with primary and secondary benzyl bromides were also elaborated. Furthermore, the application scope with alcohols, glucose, and ribose derivatives was investigated.
- Wang, Lei,Hashidoko, Yasuyuki,Hashimoto, Makoto
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p. 4464 - 4474
(2016/07/06)
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- POLYCYCLIC COMPOUNDS AS LYSOPHOSPHATIDIC ACID RECEPTOR ANTAGONISTS
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Described herein are compounds that are antagonists of lysophosphatidic receptor(s). Also described are pharmaceutical compositions and medicaments that include the compounds described herein, as well as methods of using such antagonists, alone and in combination with other compounds, for treating LPA-dependent or LPA-mediated conditions or diseases.
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Page/Page column 32
(2011/04/24)
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- High-throughput method for determining the enantioselectivity of enzyme-catalyzed hydroxylations based on mass spectrometry
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(Chemical equation presented) Up to speed: An accurate, sensitive, high-throughput, and simple method for measuring the product ee value of enzyme-catalyzed hydroxylations (see scheme) is based on the use of enantiopure or enantioenriched deuterated substrates and mass spectrometric detection.
- Chen, Yongzheng,Tang, Weng Lin,Mou, Jie,Li, Zhi
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supporting information; experimental part
p. 5278 - 5283
(2010/10/19)
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- Palladium-catalyzed cross-coupling reaction of secondary benzylic bromides with grignard reagents
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"Chemical Equation Presented" A mild palladium-catalyzed Kumada-Corriu reaction of secondary benzylic bromides with aryl and alkenyl Grignard reagents has been developed. In the presence of the Xantphos ligand, the undesired β-elimination pathway Is minimized, affording the corresponding cross-coupling products In acceptable to good yields. The reaction proceeds with inversion of the configuration.
- Lopez-Perez, Ana,Adrio, Javier,Carretero, Juan C.
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supporting information; experimental part
p. 5514 - 5517
(2010/02/28)
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- Kinetics and mechanism of nickel reaction with benzyl bromide in dimethylformamide
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Abstarct: The reaction of nickel with benzyl bromide in DMF has been studied. The reaction intermediates were investigated by different methods and the kinetic and thermodynamic parameters were determined. The reaction of benzyl bromide with nickel was shown to occur on the metal surface by the Langmuir-Hinshelwood scheme, with the formation of benzyl radicals which are recombined and isomerized in solution to form 1,2-diphenylethane and trace amounts of 4.4'-dimethylbiphenyl.
- Egorov,Matyukhova,Kocherova,Novikova,Anisimov
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experimental part
p. 444 - 452
(2009/06/28)
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- A mild synthesis of nitriles by von Braun degradation of amides using triphenyl phosphite-halogen-based reagents
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A mild procedure for the synthesis of aromatic and aliphatic nitriles is disclosed. In the presence of bromotriphenoxyphosphonium bromide (TPPBr 2), N-alkyl and N,N-dialkyl amides undergo von Braun degradation to nitriles in good to excellent yields under the mildest conditions ever reported. The reaction proceeds via formation of an iminoyl bromide intermediate at -60°C, which subsequently dealkylate upon refluxing in chloroform or even at room temperature. In the case of N-tert-butyl, N-α-phenylethyl and N-benzhydryl amides, chlorotriphenoxyphosphonium chloride (TPPCl2) generated at -30°C was also effective. Georg Thieme Verlag Stuttgart.
- Vaccari, Daniele,Davoli, Paolo,Spaggiari, Alberto,Prati, Fabio
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experimental part
p. 1317 - 1320
(2009/04/06)
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- Enantiodiscrimination of racemic electrophiles by diketopiperazine enolates: asymmetric synthesis of methyl 2-amino-3-aryl-butanoates and 3-methyl-aspartates
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Enolates of (S)-N,N′-bis-(p-methoxybenzyl)-3-iso-propylpiperazine-2,5-dione exhibit high levels of enantiodiscrimination in alkylations with (RS)-1-aryl-1-bromoethanes and (RS)-2-bromoesters, affording substituted diketopiperazines containing two new stereogenic centres in high de. Deprotection and hydrolysis of the resultant substituted diketopiperazines provides a route to the asymmetric synthesis of homochiral methyl 2-amino-3-aryl-butanoates and 3-methyl-aspartates in high de and ee.
- Bull, Steven D.,Davies, Stephen G.,Epstein, Simon W.,Garner, A. Christopher,Mujtaba, Nadeam,Roberts, Paul M.,Savory, Edward D.,Smith, Andrew D.,Tamayo, Juan A.,Watkin, David J.
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p. 7911 - 7925
(2007/10/03)
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- Enantioselective synthesis of (S)-α-arylpropionic acids via Pd-catalyzed kinetic resolution of benzylic alcohols
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A convenient synthetic route for the synthesis of three (S)-α-propionic acids, (5)-naproxen (90% ee), (S)-ibuprofen (82% ee) and (5)-phenylpropionic acid (92% ee) is described. Pd-catalyzed oxidative kinetic resolution of the corresponding benzylic alcohols is used as a key step to introduce stereogenicity into the molecule.
- Thakur, Vinay V.,Sudalai
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p. 557 - 562
(2007/10/03)
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- New Homochiral Ligands Bearing Nonstereogenic Chirotopic Centers. Lithiated N,N′-Dialkylureas as Chiral Bases and Sterically Crowded Phosphines for Asymmetric Catalysis
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The synthesis of new homochiral pseudo-C2-symmetrical ligands of type 1 bearing a nonstereogenic chirotopic center is reported. Two such structural units are combined in the ureas 2 and 10, which proved to be useful for enantioselective deprotonation and alkylation of ketones (up to 88% ee). The monophosphine 3 induced a high enantiomeric excess in the Pd-catalyzed allylation of dimethyl malonate (up to 73% ee). Furthermore, we have shown that the achiral sterically crowded alkyl diphosphine 23 efficiently stabilized Pd(0) at high temperatures.
- Graf, Claus-Dieter,Malan, Christophe,Harms, Klaus,Knochel, Paul
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p. 5581 - 5588
(2007/10/03)
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- Preparation of chiral 1-phenylethanols and bromides
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A fast, convenient procedure for preparing and resolving moderate to large quantities of chiral secondary alcohols is described.The general procedure involves a one-pot conversion of the ketone (various acetophenones) to the half-ester of a diacid (succinic, phthalic...) and resolution with (+)- and (-)-1-phenylethylamines.Overall yields of the enantiomeric alcohols, the variously substituted 1-phenylethanols, are generally 65-85percent with optical purities of approximately 90percent.Properties and optical rotations of a number of chiral 1-phenylethanols and of the bromides made from them are tabulated.A discussion of optical purity determinations using nmr methods is included and absolute configurations are reported.
- Stein, Allan R.,Dawe, Robert D.,Sweet, James R.
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p. 3442 - 3448
(2007/10/02)
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- Occurrence of Electron Transfer in the Reduction of Organic Halides by LiAlH4 and AlH3
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A variety of methods have been utilized to detect the occurrence of a single electron transfer pathway in the reduction of alkyl halides by LiAlH4 and AlH3, i.e., (1) product studies of reduction of cyclizable alkyl halides containing the 5-hexenyl group, (2) trapping of intermediate radicals by dicyclohexylphosphine and other trapping agents, (3) direct EPR observation of the trityl radical in the reduction of trityl bromide, and (4) stereochemical studies of the reduction of secondary halides by lithium aluminum deuteride.The extent of electron transfer was found to be a function of the solvent, the substrate, the leaving group, and the hydride reagent.For alkyl iodides, and to a lesser extent bromides, electron transfer was found to be the major reaction pathway; however, no evidence for electron transfer was found for the corresponding chlorides or tosylates.Reduction of (+)-2-octyl iodide by LiAlD4 was found to be much less stereospecific than the corresponding reduction of bromide, chloride, or tosylate, indicating intermediate radical formation in the reduction of the secondary iodide.
- Ashby, E. C.,DePriest, R. N.,Goel, A. B.,Wenderoth, Bernd,Pham, Tung N.
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p. 3545 - 3556
(2007/10/02)
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