- Mechanism of the deprotonation reaction of alkyl benzyl ethers with n-butyllithium
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Kinetic study of the α-lithiation of benzyl methyl ether (BME) by nBuLi has revealed that increasing the concentration of the organolithium compound does not necessarily increase the reactivity, and this is a consequence of the reactivities of the differe
- Raposo, M. Luz,Fernandez-Nieto, Fernando,Garcia-Rio, Luis,Rodriguez-Dafonte,Paleo, M. Rita,Sardina, F. Javier
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p. 9677 - 9685
(2013/07/26)
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- 6,12-Diphenyldibenzo[b,f][1,5]diazocine as an electron-capture agent: Efficient mechanistic probe for SET processes and reagent for the oxidative dimerization of benzylic organometallics
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In the present study, 6,12-diphenyldibenzo[b,f][1,5]diazocine, which X-ray diffraction measurements have now shown to possess a tub-shaped, eight-membered central ring, has been treated with sodium or lithium metal at 25 °C in THF, in an attempt to form the planar, Hueckel-aromatic dianion by the addition of two electrons to the central diazocine. Hydrolysis of such an aromatic dianion should have led to the isomeric 5,12- or 5,6-dihydro derivative of the original diazocine. In actuality, the only product obtained quantitatively upon hydrolytic workup was the interesting quadricyclic transannular reduction product, 4b,9b-diphenyl-4b,5,9b,10-tetrahydroindolo[3,2-b]indole, whose 3D structure has now been confirmed by X-ray crystallography and 13C NMR spectroscopy. Preferential SET transannular reduction of the diazocine to yield the quadricyclic indolo[3,2-b]indole dianion, rather than the planar, Hueckel-aromatic anion, is ascribed to the transannular electronic stabilization operative in the tub-shaped diazocine radical-anion. The quantitative generation of the indolo[3,2-b]indole dianion can be employed for the oxidative dimerization of the organic groups in benzylic lithium reagents. Thus treating one equivalent of the diazocine with two equivalents of benzyllithium, benzhydryllithium, or trityllithium yields quantitatively bibenzyl, 1,1,2,2-tetraphenylethane, or (4-benzhydrylphenyl)triphenylmethane, respectively. This oxidative dimerization is potentially of practical preparative scope, since the hydrolysis byproduct, the indolo[3,2-b]indole, is conveniently reconverted into the starting diazocine reagent by oxidation with chromium trioxide in acetic acid. The formation of the indolo[3,2-b]indole as a byproduct in the carbometalation of the diazocine by various RLi and Grignard reagents offers a clue as to the SET mechanism of carbometalation. Copyright
- Eisch, John J.,Yu, Kun,Rheingold, Arnold L.
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experimental part
p. 3165 - 3171
(2012/06/30)
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- A facile approach to highly efficient and thermally stable solid-state emitters: Knitting up aie-active tpe luminogens by aryl linkers
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A facile approach to thermally stable and efficient solid-state emitters is proposed. By hooking up tetraphenylethene (TPE) units through aryl linkers under Suzuki coupling conditions, a series of arylene bis(tetraphenylethene)s (TPE-Ar-TPE Ar=2,5- dimeth
- Chan, Carrie Yin Kwan,Lam, Jacky Wing Yip,Zhao, Zujin,Deng, Chunmei,Chen, Shuming,Lu, Ping,Sung, Herman H. Y.,Kwok, Hoi Sing,Ma, Yuguang,Williams, Ian D.,Tang, Ben Zhong
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p. 949 - 958
(2014/01/17)
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- METHOD FOR PRODUCING ORGANIC ALKALI METAL COMPOUND AND METHOD FOR PRODUCING ORGANIC TRANSITION METAL COMPOUND
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[Problem] To provide a preparation process by which an organic alkali metal compound is obtained in a high yield and a process for preparing an organic transition metal compound using the organic alkali metal compound. [Means to solve the problem] A process for preparing an organic alkali metal compound, which is characterized by adding a compound represented by the following formula (2) in the reaction of an active proton-containing compound represented by the following formula (1) with an alkali metal compound. In the formula (1), R is a hydrocarbon group or an amino group and may contain a halogen atom, a silicon atom, an oxygen atom or a nitrogen atom, H is an active proton, and p is the number of hydrogen atoms abstracted in the reaction with the alkali metal compound. In the formula (2), Ra to Rc are each an atom or a group selected from a hydrogen atom, a hydrocarbon group, a heteroatom-containing group and a silicon-containing group and may be the same as or different from each other, and the neighboring substituents may be bonded to each other to form a ring.
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Page/Page column 14
(2010/09/17)
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- BESTIMMUNG DER IONENPAAR-BASIZITAT VON LITHIUM- UND KALIUMAMIDEN
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Ion pair basicities of lithio and potassio salts of some secondary amines were determined by equilibration with benzyl compounds.With these bases it is possible to span a range of about 19 pK-units from pK = 27 up to 46.The structural dependence of thermodynamic as well as kinetic basicity is discussed.Some new effective amide bases for preparative purposes are recommended.For the first time the pK-value of toluene has been determined by direct equilibration.It amounts to 40.7 in tetrahydrofuran.
- Ahlbrecht, Hubertus,Schneider, Gunther
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p. 4729 - 4742
(2007/10/02)
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- Carbanion Rearrangements by Intramolecular 1,ω Proton Shifts, IV. The Reaction of ω,ω-Diphenylalkyllithium Compounds: Proof for an Intramolecular Transmetallation Reaction by Crossover Experiments Using Isotopic Labelled Starting Material
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3,3-Diphenylpropyllithium (2) and 2-(9-fluorenyl)ethyllithium (43) do not show a 1,3 proton shift but splitt off ethylene.On the other hand 4,4-diphenylbutyllithium (19) in diethyl ether can be forced to rearrange to 1,1-diphenylbutyllithium (18) by the addition of THF.The half reaction time for this 1,4 proton shift was found to be about 4 minutes.Proof for the intramolecular character of this transmetallation reaction was obtained by crossover experiments with specifically deuterated starting material.The 1,5 proton shift with 5,5-diphenylpentyllithium (12) occurs considerably slower than the 1,4 shift with 4,4-diphenylbutyllithium (19).The rearrangement also takes place in pure diethyl ether although with a half reaction time of about 2 days.Only 3-(9-fluorenyl)propyllithium (41) in diethyl ether spontaneously shows rearrangement already at -30 deg C, whereby 9-propyl-9-fluorenyllithium (42) is formed by a 1,4 proton shift.A 1,ω phenyl migration according to Grovenstein-Zimmerman in no case could be observed.
- Maercker, Adalbert,Passlack, Michael
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p. 710 - 723
(2007/10/02)
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- Substituent Effect on the Electrochemical Oxidation of Arylmethyl Anions. 3. Effect of Methyl Substitution on Diarylmethyl Anions
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Electrochemical oxidation of a series of diarylmethyl anions was examined.Twelve varingly substituted groups including methyl, dimethyl, ring, and a CH2N(CH3)2 group were studied as the lithium salts in dimethoxyethane/tetramethylethylenediamine by use of
- Bank, Shelton,Schepartz, Alanna,Giammatteo, Paul,Zubieta, Jon
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p. 3458 - 3464
(2007/10/02)
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- Determination of the Basicities of Benzyl, Allyl, and tert-Butylpropargyl Anions by Anodic Oxidation of Organolithium Compounds
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Electrochemical oxidation potentials have been determined by using cyclic voltammetry and second-harmonic ac voltammetry for benzyllithium, allyllithium, tert-butylpropargyllithium, and triphenylmethyllithium in tetrahydrofuran/hexamethylphosphoramide.The
- Jaun, Bernhard,Schwarz, Joshua,Breslow, Ronald
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p. 5741 - 5748
(2007/10/02)
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