- Ruthenium-Catalyzed Reductive Arylation of N-(2-Pyridinyl)amides with Isopropanol and Arylboronate Esters
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A new three-component reductive arylation of amides with stable reactants (iPrOH and arylboronate esters), making use of a 2-pyridinyl (Py) directing group, is described. The N-Py-amide substrates are readily prepared from carboxylic acids and PyNH2, and the resulting N-Py-1-arylalkanamine reaction products are easily transformed into the corresponding chlorides by substitution of the HN-Py group with HCl. The 1-aryl-1-chloroalkane products allow substitution and cross-coupling reactions. Therefore, a general protocol for the transformation of carboxylic acids into a variety of functionalities is obtained. The Py-NH2 by-product can be recycled.
- Ronson, Thomas O.,Renders, Evelien,Van Steijvoort, Ben F.,Wang, Xubin,Wybon, Clarence C. D.,Prokopcová, Hana,Meerpoel, Lieven,Maes, Bert U. W.
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p. 482 - 487
(2019/01/04)
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- Kinetics of α-(2,6-Dimethylphenl)vinyllithium: How to Control Errors Caused by Inefficient Mixing with Pairs of Rapidly Competing Ketones
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Kinetic studies are a suitable tool to disclose the role of tiny reagent fractions. The title compound 2 reacted in a kinetic reaction order of 0.5 (square root of its concentration) with an excess of the electrophiles ClSiMe3, 1-bromobutane (n-BuBr), or 1-iodobutane (n-BuI) at 32 °C in Et2O or in hydrocarbon solvents. This revealed that the tiny (NMR-invisible) amount of a deaggregated equilibrium component (presumably monomeric 2) was the reactive species, whereas the disolvated dimer 2 was only indirectly involved as a supply depot. Selectivity data (relative rate constants κobs) were collected from competition experiments with the faster reactions of 2 in THF and the addition reactions of 2 to carbonyl compounds. This provided the rate sequences of Et2C=O > dicyclopropyl ketone > t-Bu-C(=O)-Ph > diisopropyl ketone ? t-Bu2C=O > ClSiMe3 > n-BuI > n-BuBr ≈ (bromomethyl)cyclopropane (but t-Bu2C=O 3 in THF only) and also of cyclopropanecarbaldehyde > acetone ≥ t-Bu-CH=O. It is suggested that a deceivingly depressed selectivity (1 obs A/kB), caused by inefficient microscopic mixing of a reagent X with two competing substrates A and B, may become evident toward zero deviation from the correlation line of the usual inverse (1/T) linear temperature dependence of ln κobs.
- Knorr, Rudolf,Knittl, Monika,Behringer, Claudia,Ruhdorfer, Jakob,B?hrer, Petra
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p. 2843 - 2854
(2017/03/23)
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- Hydrogenated acridine derivative and its application
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The invention relates to the field of chemical synthesis, and particularly relates to a compound with the general formula being Y-L-X and an application of the compound serving as a calcium channel blocking agent or/and an acetylcholinesterase inhibitor. The compound with the general formula being Y-L-X can be used for adjusting calcium homeostasis and treating cardiovascular diseases, stroke or dementia.
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- Luminescent Ce(III) Complexes as Stoichiometric and Catalytic Photoreductants for Halogen Atom Abstraction Reactions
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Luminescent Ce(III) complexes, Ce[N(SiMe3)2]3 (1) and [(Me3Si)2NC(RN)2]Ce[N(SiMe3)2]2 (R = iPr, 1-iPr; R = Cy, 1-Cy), with C3v and C2v solution symmetries display absorptive 4f → 5d electronic transitions in the visible region. Emission bands are observed at 553, 518, and 523 nm for 1, 1-iPr, and 1-Cy with lifetimes of 24, 67, and 61 ns, respectively. Time-dependent density functional theory (TD-DFT) studies on 1 and 1-iPr revealed the 2A1 excited states corresponded to singly occupied 5dz2 orbitals. The strongly reducing metalloradical character of 1, 1-iPr, and 1-Cy in their 2A1 excited states afforded photochemical halogen atom abstraction reactions from sp3 and sp2 C-X (X = Cl, Br, I) bonds for the first time with a lanthanide cation. The dehalogenation reactions could be turned over with catalytic amounts of photosensitizers by coupling salt metathesis and reduction to the photopromoted atom abstraction reactions.
- Yin, Haolin,Carroll, Patrick J.,Anna, Jessica M.,Schelter, Eric J.
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supporting information
p. 9234 - 9237
(2015/08/11)
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- Nickel-catalyzed asymmetric reductive cross-coupling between vinyl and benzyl electrophiles
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A Ni-catalyzed asymmetric reductive cross-coupling between vinyl bromides and benzyl chlorides has been developed. This method provides direct access to enantioenriched products bearing aryl-substituted tertiary allylic stereogenic centers from simple, stable starting materials. A broad substrate scope is achieved under mild reaction conditions that preclude the pregeneration of organometallic reagents and the regioselectivity issues commonly associated with asymmetric allylic arylation.
- Cherney, Alan H.,Reisman, Sarah E.
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supporting information
p. 14365 - 14368
(2014/12/11)
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- Catalytic asymmetric reductive acyl cross-coupling: Synthesis of enantioenriched acyclic α,α-disubstituted ketones
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The first enantioselective Ni-catalyzed reductive acyl cross-coupling has been developed. Treatment of acid chlorides and racemic secondary benzyl chlorides with a NiII/bis(oxazoline) catalyst in the presence of Mn0 as a stoichiometric reductant generates acyclic α,α-disubstituted ketones in good yields and high enantioselectivity without requiring stoichiometric chiral auxiliaries or pregeneration of organometallic reagents. The mild, base-free reaction conditions are tolerant of a variety of functional groups on both coupling partners.
- Cherney, Alan H.,Kadunce, Nathaniel T.,Reisman, Sarah E.
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supporting information
p. 7442 - 7445
(2013/06/27)
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- Two-fold modification of the phenyl substituent in phenylphosphonic acid monoester monoamides
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Phenylphosphonic acid ethyl ester N,N-diethylamide was subjected to a double modification of its phenyl substituent through directed ortho-metalation followed by dearomatization of the aryl substituent under Birch reduction conditions. Application of the same methodology to a diastereomerically pure phenylphosphonic acid monoester monoamide led to the formation of P-stereogenic cyclohexadienyl-phosphonic acid derivatives. The method offers a simple and efficient modification of phenyl substituent in organophosphorus compounds.
- Stankevic, Marek,Bazan, Jolanta
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p. 8244 - 8256
(2013/01/15)
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- Palladium-catalyzed oxidative arylhalogenation of alkenes: Synthetic scope and mechanistic insights
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This article describes the development of a Pd-catalyzed reaction for the arylhalogenation (halogen = Cl or Br) of diverse α-olefins by oxidatively intercepting Mizoroki-Heck intermediates. These transformations afford synthetically useful 1,2- and 1,1-arylhalogenated products in good yields with good to excellent selectivities that can be modulated by changing the nature of the halogenating reagent and/or the reaction conditions. The selectivity of these reactions can be rationally tuned by (i) controlling the relative rates of oxidative functionalization versus β-hydride elimination from equilibrating PdII-alkyl species and (ii) stabilization of organometallic PdII intermediates through the formation of π-benzyl adducts. These arylhalogenations exhibit modest to excellent levels of stereoselectivity, and the key carbon-halogen bond-forming step proceeds with predominant retention of stereochemistry at carbon.
- Kalyani, Dipannita,Satterfield, Andrew D.,Sanford, Melanie S.
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supporting information; experimental part
p. 8419 - 8427
(2010/08/04)
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- The leaving group dependence in the rates of solvolysis of 1,2-diphenylethyl system
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1,2-Diphenylethyl chloride undergoes solvolysis by SN1 mechanism in aqueous organic solvents. The α-phenyl group of 1,2-diphenylethyl chloride enters into conjugation with the developing carbocationic centre. The β-phenyl group on the other hand was unable to extend its conjugation via neighbouring group participation due to steric inhibition of resonance in the formation of non-classical carbocation. 1,2-Diphenylethyl chloride thus behaves similar to 1-phenylethyl chloride in its solvolysis pattern. The solvolytic rate studies of chloride and methanesulphonate of 1,2-diphenylethyl alcohol in various aqueous organic solvents show that the dispersion observed in the Winstein- Grunwald plot is not due to a change in leaving group but due to the difference in solvation requirements of aromatic and aliphatic groups. Copyright
- Santhosh Kumara,Jayakumarb,Balachandranc
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experimental part
p. 783 - 788
(2011/05/05)
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- Probing the formation of bicyclo[4.2.0]octan-1-ols
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Reaction of lithium enolates of simple ketones with (±)-phenyl vinyl sulfoxide has potential for the convergent construction of complex fused ring systems containing a bicyclo[n.2.0]alkan-1-ol. The formation of sulfinylbicyclo[4.2.0]octan-1-ols 1-3 from the lithium enolate of cyclohexanone with (±)-phenyl vinyl sulfoxide or (R)-(+)-p-tolyl vinyl sulfoxide 18 was used to probe the mode of this novel cyclization reaction. Using phenyl vinyl sulfoxide, variations in the reaction lighting and solvent were investigated, in conjunction with radical trapping (TEMPO) and isotope labeling (deuterium) experiments. Cyclization to form sulfinylbicyclooctanols 1-3 is likely to proceed via an intermediate that ring closes to the bicycloalkanol anion 11 and was presently favored by the use of solvents such as THF or DME.
- Loughlin, Wendy A.,Rowen, Catherine C.,Healy, Peter C.
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p. 5690 - 5698
(2007/10/03)
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- The 1,2-diphenylethyl cation via carbene fragmentation
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2,2-Diphenylethoxychlorocarbene fragments with kfrag=2.1×106 s-1 in MeCN, largely with 1,2-phenyl migration and the formation of rearranged products. Related chemistry is observed for the 2,2-diphenylethyldiazonium cation.
- Moss, Robert A,Ma, Yan
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p. 6045 - 6048
(2007/10/03)
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- Catalytic Effect of Ferrous Chloride in Chloroarylation of Styrene
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Styrene reacts with arenediazonium chlorides in the presence of FeCl2 as catalyst to give 1-chloro-1-phenyl-2-arylethanes along with minor amounts of 1,4-diaryl-2,3-diphenylbutanes. Ferrous chloride turned out to be a more active catalyst in the chloroarylation of styrene than copper chlorides.
- Obushak
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p. 443 - 445
(2007/10/03)
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- A method for generation of α-halo carbanions (carbenoids) from aryl α-haloalkyl sulfoxides with alkylmetals
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Ligand exchange reaction of simple aryl α-haloalkyl sulfoxides with alkyllithium and ethylmagnesium halide at low temperature was investigated. On treatment of aryl α-haloalkyl sulfoxide with n-BuLi, t-BuLi, or EtMgX exclusively sulfur-alkyl bond-cleavage took place to afford α-halo carbanion (carbenoid). When this reaction was carried out without a proton source, the intermediate α-halo carbanion decomposed to give olefines in good yield. The ligand exchange reaction of sulfoxide was found to be very fast and the reaction could be carried out with a proton or a deuterium source (internal quench) to afford alkyl halide. This procedure offers a new method for preparing α-deuterated) halides (the halogen is F, Cl, or Br).
- Satoh, Tsuyoshi,Takano, Koji
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p. 2349 - 2358
(2007/10/03)
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- Carbonyl Addition and Alkylation Reactions of Isothiazolidine 1-Oxide, the Sulfur Analog of 2-Pyrrolidone
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Isothiazolidine 1-oxide is the sulfur analog of 2-pyrrolidone.A series of reactions at both the nitrogen and the α-sulfinyl carbon have been carried out.N-Deprotonation under phase-transfer conditions in the presence of p-nitrobenzyl bromide gives 2-(p-ni
- Semko, Christopher M.,Casale, Kristin G.,Doi, Joyce Takahashi,Musker, W. Kenneth
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p. 696 - 699
(2007/10/02)
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- THE REACTION OF BENZYLIC ALCOHOLS WITH CHLOROTRIMETHYLSILANE/DIMETHYL SULPHOXIDE
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With catalytic amounts of chlorotrimethylsilane/dimethyl sulphoxide (CTMSO/DMSO) in acetonitrile benzylic alcohols have been found to give high yields of styrenes.By using stoicheiometric amounts of reagents, different reaction pathways are observed: an elimination-addition sequence occurs with secondary and tertiary alcohols affording vicinal dichloro derivatives, β-chloro thioethers and allyl chlorides, whereas a nucleophilic substitution to the corresponding monochlorides occurs starting from primary and sterically hindered substrates.
- Bellesia, Franco,Ghelfi, Franco,Pagnoni, Ugo Maria,Pinetti, Adriano
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p. 437 - 439
(2007/10/02)
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- Unusual 1,3-Rearrangement of Trimethylsilyl Group in the Reaction of 2,4,6-Trisphenyllithium
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2,4,6-Trisphenyllithium (TbLi) gave a novel 1,3-silicon rearrangement product above -30 deg C, while the treatment of TbLi with some electrophiles also afforded 1,3-silicon rearrangement products even at -78 deg C probably via single electron transfer mechanism.
- Tokitoh, Norihiro,Matsumoto, Tsuyoshi,Suzuki, Hiroyuki,Okazaki, Renji
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p. 2049 - 2052
(2007/10/02)
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- REACTIVITY AND SELECTIVITY IN INTERMOLECULAR INSERTION REACTIONS OF CHLOROPHENYLCARBENE
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Reactivities for intermolecular C-H/Si-H/Sn-H insertion reactions of chlorophenylcarbene follow the order tri-n-butyltin hydride>>diphenylsilane>triethylsilane>>cumene>ethylbenzene>>toluene, and these reactions are competitive with addition to the double bond of α,β-unsaturated esters.
- Doyle, Michael P.,Taunton, Jack,Oon, Su-Min,Liu, Michael T. H.,Soundararajan, N.,et. al.
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p. 5863 - 5866
(2007/10/02)
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- Multifunctional Photoadditions of Stilbene to Derivatives of Caffeine and Benzothiazole
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Electronically excited stilbene (1*) is trapped by 8-substituted caffeine derivatives (2a-f) or 2-chloro- (14) and 2-aminobenzothiazole (21) with variable results.While the electron-rich systems (2c,d) produce mostly propellanes, the halogeno compounds 2a,b and 14 react predominantly via insertion into the C-halogen bond.With 14 there occurs also some C-S insertion, with 21 only N-H insertion.Numerous succeeding reactions are elucidated and the reaction mechanisms discussed.Stilbene (1) photoadds hydrogen chloride to yield 16.
- Kaupp, Gerd,Ringer, Ernst
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p. 1525 - 1539
(2007/10/02)
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- Arylation of olefins
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An olefin, especially an activated olefin, is arylated by reaction with an arylamine, such as an aniline, in an inert polar organic solvent and in the presence of an alkyl nitrite, a hydrogen halide, and a catalytic amount of a copper catalyst having the copper in an oxidation state below +2.
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- Studies on Intramolecular Cycloaddition Reactions of Some Isoquinolinium Salts
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Thermally-induced intramolecular addition reactions of isoquinolinium derivatives bearing an alkenyl side-chain have been studied.Cycloadditions can occur across the isolated olefinic bond and the 1,4-positions of the isoquinolinium system to produce tetracyclic adducts.The chemistry of these adducts is compared with that of cycloadducts produced in intramolecular additions.Preparation of some of the isoquinoline derivatives involved alkylation of the parent base; 3-metylisoquinoline can be substituted either at the methyl group, upon reaction with aromatic nitriles or at C-4, using alkyl halides.
- Gisby, Graham P.,Sammes, Peter G.,Watt, Robert A.
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p. 249 - 256
(2007/10/02)
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- PYRIDINES. PARTIE IX - PLURIBENZYLATION DE LA S-COLLIDINE ET DE LA LUTIDINE-2,6
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A literature survey of the polymetalation of 2,6-lutidine 2 shows different results about the site(s) of deprotonation and condensation with various electrophiles.This discrepancy prompts us to examine the polylithiation (PhLi 3 equivalents, Et2O) of s-collidine 1, 2,6-lutidine 2 and more briefly of 2,4-lutidine 3.Polylithiation takes place exclusively at the methyl groups of the same position vs the ring nitrogen : 2- and/or 6-methyl of 1.The previous regioselectivity observed in the case of the monometalation in Et2O is maintained.From 1 and 2, polylithiation gives picolyl anions which lead by reaction with PhCH2Cl, simultaneously to mono-, di-symmetrical, di-non-symmetrical α-derivatives, and tri- and tetra-symmetrical α,α'-compounds; but no product is formed from a benzylic β-anion.In the same way, the deprotonation of 2-methyl-6-(2-phenylethyl) pyridine 17 leads to 2,6-bis (2-phenylethyl) pyridine 19 and 2-methyl-6-dibenzylmethyl pyridine 18, to the exclusion of the β-compound 2-methyl-6-(2,3-diphenylpropyl) pyridine 21.The latter compound is formed in low yield, besides 19 and 18, in the conditions of the Tchitchibabine reaction (NaNH2, toluene).The structure of the benzylated compounds was established mainly from the 1H-nmr data.No product was isolated which would result from the nucleophilic attack of the generated carbanions at the pyridine carbons.
- Compagnon, Paul-Louis,Kimny, Tan,Gasquez, Francoise
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p. 803 - 816
(2007/10/02)
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- REARRANGEMENTS OF THE CARBANIONS DERIVED FROM ALLYL BENZYL THIOETHER
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The metalation of allyl benzyl thioether involves the benzylic or the allylic hydrogens.The benzylic carbanion undergoes a rapid sigmatropic shift whereas the allylic carbanion gives rise to various rearrangements, among them migration of the allylic unit to the para position with allylic inversion.The temperature dependence of the ratio of products arising from the benzylic carbanion vs those from the allylic carbanion shows that the allylic-to-benzylic carbanion transformation occurs only under special conditions: (a) with slow addition of the base; (b) with thioether in excess relative to the base, and (c) on raising the temperature of the reaction medium from -78 deg C to -15 deg C.In the last instance, the proton transfer is intramolecular as shown with labeled thioethers.The extent of the different rearrangements depends on the temperature and solvent.A choise of mechanism cannot be made at this time for the para migration 5-->9a.A leaving group effect on the reaction regioselectivity of the carbanion from allyl methyl thioether with benzyl halides has been noticed.The presence of dibenzyl indicates that, in addition to SN2 reactions, some electron transfer process is occuring.
- Biellmann, J. F.,Ducep, J. B.,Schirlin, D.
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p. 1249 - 1260
(2007/10/02)
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