- Phosphorus-Containing Block Copolymers from the Sequential Living Anionic Copolymerization of a Phosphaalkene with Methyl Methacrylate
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Although living polymerization methods are widely applicable to organic monomers, their application to inorganic monomers is rare. For the first time, we show that the living poly(methylenephosphine) (PMPn?) anion can function as a m
- Chen, Leixing,Rawe, Benjamin W.,Adachi, Kaoru,Gates, Derek P.
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- Directional properties of fluorenylidene moieties in unsymmetrically substituted N-heterocyclic carbenes. Unexpected CH activation of a methylfluorenyl group with palladium. Use in palladium catalysed Suzuki-Miyaura cross coupling of aryl chlorides
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Benzimidazolium salts having their two nitrogen atoms substituted by different 9-alkylfluorenyl groups (4a-e and 4g, alkyl1/alkyl 2 = Me/Et, Me/Pr, Me/n-Bu, Me/i-Pr, Me/Bn, Me/CH2SMe have been synthesised in high yields in two or three steps from N,N′-bis(9H- fluoren-9-ylidene)benzene-1,2-diamine (1). The imidazolium salts 4a-e were converted readily into the corresponding PEPPSI-type palladium complexes (PEPPSI = pyridine-enhanced precatalyst preparation stabilisation and initiation), while reaction of the methylthioether-substituted salt 4g with PdCl 2/K2CO3/pyridine afforded the palladacycle 5g resulting from metallation of the methyl group attached to the fluorenylidene moiety. NMR and X-ray diffraction studies revealed that the carbene ligands in 5a-5e behave as clamp-like ligands, the resulting metal confinement arising from a combination of the orientational properties of the fluorenylidene moieties that push the alkyl groups towards the metal centre and attractive anagostic interactions involving CH2(fluorenyl) groups. Complexes 5a-e were assessed in Suzuki-Miyaura cross-coupling reactions. Like their symmetrical analogues they displayed high activity in the coupling of phenyl boronic acid with p-tolylchloride but their performance remained slightly inferior to that of the related, symmetrical Et/Et complex 5h.
- Teci, Matthieu,Brenner, Eric,Matt, Dominique,Gourlaouen, Christophe,Toupet, Loic
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p. 12251 - 12262
(2014/08/05)
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- Isomerization polymerization of the phosphaalkene MesP=CPh2: An alternative microstructure for poly(methylenephosphine)s
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Unique pathway: The radical-initiated addition polymerization of MesP=CPh2 propagates through the ortho-bound CH3 group of the Mes moiety after C-H bond activation (see scheme, Mes=2,4,6-trimethylphenyl, tht=tetrahydrothiophene, TEMPO=2,2,6,6-tetramethyl-l-piperidinoxyl). This unique isomerization polymerization mechanism contrasts the previously suggested head-to-tail enchainment typically observed for olefins. Copyright
- Siu, Paul W.,Serin, Spencer C.,Krummenacher, Ivo,Hey, Thomas W.,Gates, Derek P.
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supporting information
p. 6967 - 6970
(2013/07/26)
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- Arylcalcium iodides in tetrahydropyran: Solution stability in comparison to aryllithium reagents
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Reduction of para-substituted iodobenzene in tetrahydropyran (THP) with finely dispersed calcium powder yields arylcalcium iodides of the type [(THP)4Ca(C6H4-4-R)I] with R = CH3 (1), Cl (2), Br (3), I (4), OCH3 (5). A 2-fold insertion of calcium into dihalobenzenes was not observed. The β-naphthylcalcium iodide [(THP)4Ca(β-Naph)I] (6) is also accessible by direct synthesis in THP. The durability of arylcalcium compounds in THP was studied in comparison to that in THF, and a slightly enhanced lifetime in THP at ambient temperature was observed. Furthermore, the relative reactivity and selectivity of 1 and its lithium counterpart [{(THP)2Li}2(μ-Tol)(μ-Br)] (7) in the reaction with THP and THF were studied. α-Metalation and subsequent cycloreversion was the major pathway observed for THF in both cases. In the degradation reaction induced by 7, several byproducts arising from carbolithiation and, surprisingly, from β-metalation reactions were identified, while 1 was found to be more selective. The related [(THP) 2Li(μ-Ph)]2 (9) was prepared and used to unambiguously identify some of the products. In order to verify the formation of benzyllithium as one of the byproducts, an authentic sample of [(dme)Li(μ-CH 2Ph]2 (8) was prepared. In THP, an inversion of the relative reactivity of 1 and 7 was observed and the calcium compound was found to be more reactive than its lithium analogue. The crystal structures of 1-9 were determined by X-ray diffraction studies, and a trans arrangement of the anionic ligands due to electrostatic reasons was observed in case of the hexacoordinated calcium complexes.
- Langer, Jens,Koehler, Mathias,Fischer, Reinald,Duendar, Feyza,Goerls, Helmar,Westerhausen, Matthias
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p. 6172 - 6182
(2012/10/29)
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- Production of benzyllithium, benzylsodium, and polyphenylene paradimethylene
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A process for producing benzyllithium, benzylsodium and polyphenylene paradimethylene and analogs comprising dissolving toluene in an aprotic polar solvent in which toluene is more acidic than water, such as DMSO, under an inert atmosphere, such as argon, adding an alkali metal hydroxide, such as lithium or sodium hydroxide, to form the alkali metal anion of the benzyl cation and water then removing the solvent and water to obtain the solid alkali metal alpha-carbon toluene compound, which is best stored under hexane. This process also relating to toluene analogs such as parachloro toluene which thereby yields parachloro alkali metal alpha-carbon toluene which is then polymerized by heating with a suitable high-boiling solvent, such as dibutyl ether or dimethoxy ethane in the presence of a copper catalyst, such as copper sulfate or finely divided copper metal at approximately 170C for 5 hours to form polyphenylene paradimethylene. This process having the advantage of using alkali metal hydroxides instead of elemental alkali metals, a reaction occurring at ordinary temperatures, and a lower cost of the product. This process also allowing the economical production of polyphenylene paradimethylene which is not currently being manufactured.
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Page/Page column 1
(2008/06/13)
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- 1,3,5-SUBSTITUTED PHENYL DERIVATIVE COMPOUNDS USEFUL AS BETA-SECRETASE INHIBITORS FOR THE TREATMENT OF ALZHEIMER'S DISEASE
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The present invention is directed to 1,3,5-phenyl substituted derivative compounds which are inhibitors of the beta-secretase enzyme and that are useful in the treatment of diseases in which the beta-secretase enzyme is involved, such as Alzheimer's disease. The invention is also directed to pharmaceutical compositions comprising these compounds and the use of these compounds and compositions in the treatment of such diseases in which the beta-secretase enzyme is involved.
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Page/Page column 112-113
(2010/02/14)
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- Reductive lithiation of alkyl phenyl sulfides in diethyl ether. A ready access to α,α-dialkylbenzyllithiums
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Diethyl ether is a convenient solvent for the conversion of benzylic phenyl sulfides to the corresponding organolithiums by an uncatalyzed reductive metalation, while catalysis by naphthalene is required to achieve the same reaction for alkyl phenyl sulfides. The addition of magnesium 2-ethoxyethoxide to solutions of unstable alkyllithiums prepared in this way provides storable reagents.
- Screttas, Constantinos G.,Heropoulos, Georgios A.,Micha-Screttas, Maria,Steele, Barry R.,Catsoulacos, Dimitrios P.
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p. 5633 - 5635
(2007/10/03)
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- ROMPgel-supported biphenyl and naphthalene: Reagents for lithiation reactions with minimal purification
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The synthesis of ring opening metathesis, polymer (ROMPgel) supported naphthalene and biphenyl reagents was carried out. These reagents were utilized for catalytic lithiation reactions of aryl and alkyl chlorides and for the reductive deprotection of benzyl and allyl ethers.
- Arnauld, Thomas,Barrett, Anthony G.M.,Hopkins, Brian T.
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p. 1081 - 1083
(2007/10/03)
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- Intermediates for the preparation of cyclic urea
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This invention relates to novel compounds and derivatives thereof containing a trioxepane protected diol in addition to a hydrazone, hydrazine, amine, or cyclic urea moiety; methods for the preparation of said compounds; and the use of said compounds in p
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- The preparation of pure allyl- and benzyl-type organoalkali intermediates via organotin compounds
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Superbase metalation of alkenes or alkylbenzenes and subsequent condensation with trialkylstannyl chloride affords allyl- or benzyl-type organotin compounds that can be isolated in pure form.Treatment with soluble reagents such as methyllithium, trimethylsilylmethylpotassium and trimethylsilylmethylcaesium generates the corresponding organoalkali derivatives almost quantitatively and in high purity, suitable for kinetic or spectroscopic studies.
- Desponds, Olivier,Schlosser, Manfred
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- Stereoselective Synthesis of 2Z,4E-Dienals by Addition of Organometallic Reagents to Pyrylium Perchlorate
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A facile and stereoselective approach to 2Z,4E-dienals and derived products is presented.The method involves addition of an organometallic reagent to a pyrylium salt, followed by electrocyclic ring-opening of the intermediate 2H-pyran, to give the desired Z,E-dienal, usually with greater than 95percent stereochemical purity.These dienals may be trapped in situ with a second organometallic reagent, or oxidised or redused, without loss of stereochemical integrity.The synthesis of (1,3Z,5E)-undeca-1,3,5-triene, a component of the essential oils of the brown Hawaiian seaweeds Dictyopteris plagiogramma and D. australis, is reported to illustrate the simplicity of the procedure.
- Furber, Mark,Herbert, John M.,Taylor, Richard J. K.
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p. 683 - 690
(2007/10/02)
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- QUANTUM CHEMICAL CALCULATIONS AND NUCLEAR MAGNETIC RESONANCE MEASUREMENTS ON BENZYL-TYPE CARBANIONS. PART 2. INFLUENCE OF COUNTERCATIONS AND INTERACTING UNSATURATED SYSTEMS
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Quantum chemical calculations, n.m.r. and spectrophotometric measurements are carried out to study the influence of countercations and interacting unsaturated systems on the structural and electronic properties of benzyl-type carbanions.The calculated geometry of benzyl-Li compares favourably with X-ray data on a related structure. (13)C, (1)H n.m.r. shifts and 1JCH coupling constants of benzyl, o- and p-CH3O-benzyl-Li, -Na, and -K compounds show a fair overall agreement with the ab initio-calculated charge distributions and structural parameters for the terminal members of the Li-, Na-, and K- series, the Li compound and the free carbanion, modelling the K salt.Both theory and experiment indicate that, when passing from the anion to the alkali-metal compound, an important destruction of the resonance saturation, present in the CH3O derivatives, occurs due to the presence of the countercation, the reduction being more important with decreasing cation radius.The n.m.r. data for α-alkyl-substituted compounds suggest that steric factors make the position of the cation in the Cα region less favourable, the effect being more pronounced for larger cation radius.The resonance saturation effect in the above mentioned systems may also be influenced by intermolecular effects, e.g. it may change during a chemical reaction.Ab initio calculations on the interaction energy between the benzyl-type carbanions and unsaturated systems showing increasing delocalization possibilities for incoming negative charge indicate that the larger this delocalization possibility (ethene butadiene styrene), the more important the destruction of resonance saturation.Along this series the parallel conformation of the CH3O group in the p-CH3O compounds gradually becomes less disfavoured.The calculated effect is however not strong enough yet in order to show full agreement with the observed increase in the k(-) value for the addition reaction to 1,1-diphenylethene when passing from polystyryl to poly-p-methoxystyryl carbanions.Larger basis sets and extensive geometry optimization should be carried out in order to settle this problem.
- Vanermen, Guido,Toppet, Suzanne,Van Beylen, Marcel,Geerlings, Paul
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p. 707 - 714
(2007/10/02)
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- Dissociation Behavior of Benzylalkali Compounds in Tetrahydrofuran: Effect of Countercation, Aromatic Methoxy Substitution, and α-Alkyl Substitution
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Conductometric measurements are carried out on different benzylalkali compounds (benzylcesium, -potassium, -sodium, and -lithium, and their o-CH3O and p-CH3O derivatives) in tetrahydrofuran at various temperatures, in order to get information on their dissociative behavior and on the influence of the alkali cation, aromatic methoxy substitution, and α-alkyl substitution on the carbon-metal bond strength.The dissociation constants of the organometallic compounds are determined by using the Kraus and Bray equation, the Fuoss equation, the Wooster equation, or by curve fitting depending on which species are involved in the solution conductance.Temperature variation of Kd is used to determine the enthalpy and entropy of dissociation.The information previously acquired by quantum chemical calculations and NMR measurements on the electronic structure of benzyl-type carbanions and the corresponding organometallic compounds appears to be of great value in interpreting the dissociation behavior of the benzyl- and styrylalkali compounds (which are also included in the study).The resonance saturation phenomenon encountered in the quantum chemical and NMR study turns out to be an important factor in the dissociative behavior of p-CH3O compounds, as compared to the unsubstituted cases.The smaller dissociation costants of the o-CH3O compounds also parallel the results of the quantum chemical calculations, showing an additional interaction between the cation and the CH3O group.The weakening of the carbon-metal bond upon α-alkyl substitution parallels the increase of dissociation capability when alkyl or polymer chain substituents are present on the α-carbon atom.
- Vanermen, G.,Beylen, M. Van,Geerlings, P.
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p. 603 - 607
(2007/10/02)
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- ZUR BILDUNGSWEISE VON 1-PHENYLPROPYLLITHIUM AUS BENZYLLITHIUM UND ETHYLEN IN TETRAHYDROFURAN
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3-Phenylpropyllithium primarily formed by the addition of benzyllithium to ethylene in THF does not undergo an intramolecular 1,3-proton shift to 1-phenylpropyllithium.Fast protonation by the solvent takes place instead, yielding n-propylbenzene and new ethylene.An equilibrium is then established between n-propylbenzene and additional benzyllithium, with the formation of toluene and 1-phenylpropyllithium; the equilibrium, however, strongly favours the starting materials (K293=1.1*10-4).As, on the other hand, 1-phenylpropyllithium reacts with ethylene much more rapidly than does benzyllithium, it is removed from the equilibrium and mainly branched secondary products are still obtained.
- Maercker, Adalbert,Stoetzel, Reinhard
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- 2-Benzyl-4-piperidones useful as intermediates in the production of 6,7-benzomorphan derivatives
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6,7-BENZOMORPHAN DERIVATIVES HAVING ANALGESIC AND MORPHINE-ANTAGONISTIC PROPERTIES ARE OF THE FORMULA STR1 in which the substituents R are either lower alkyl groups or groups which, together with the carbon atom to which they are bonded, form a cycloaliphatic ring, and the substituents R1, R2 and R 3 may or may not be made and, if made, R1 represents either a hydrogen atom or an alkyl, haloalkyl, alkenyl, alkinyl, aralkyl, cycloalkenyl, cycloalkylalkyl, cycloalkenylalkyl or cycloalkylidine-alkyl group, R 2 is an alkyl, aryl, heteroaryl or aralkyl group, and R 3 is a hydrogen atom or an hydroxy, alkoxy, alkoxy-alkoxy or acyloxy group. Such 6,7-benzomorphans may be in the form of their optically active enantiomers and/or their therapeutically acceptable salts. There are also disclosed methods for producing such 6,7-benzomorphan derivatives, and intermediates useful in such production.
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