- Reactivity of phospha-Wittig reagents towards NHCs and NHOs
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Phospha-Wittig reagents, RPPMe3(R = Mes* 2,4,6-tBu3-C6H2;MesTer 2,6-(2,4,6-Me3C6H2)-C6H3;DipTer 2,6-(2,6-iPr2C6H
- Gupta, Priyanka,Siewert, Jan-Erik,Wellnitz, Tim,Fischer, Malte,Baumann, Wolgang,Beweries, Torsten,Hering-Junghans, Christian
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supporting information
p. 1838 - 1844
(2021/02/16)
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- Elevated reaction order of 1,3,5-tri-tert-butylbenzene bromination as evidence of a clustered polybromide transition state: a combined kinetic and computational study
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The kinetics and mechanism of concurrent bromo-de-protonation and bromo-de-tert-butylation of 1,3,5-tri-tert-butylbenzene at different bromine concentrations were studied experimentally and theoretically. Both reactions have high order in bromine (experimental kinetic orders ~5 and ~7, respectively). According to quantum chemical DFT calculations, such high reaction orders are caused by participation of clustered polybromide anions Br2n?1- in transition states. Bromo-de-tert-butylation has a higher order due to its bigger reaction center demanding clusters of extended size. A significant primary deuterium kinetic isotope effect (KIE) for bromo-de-protonation is measured indicating proton removal is rate limiting, as confirmed by computed DFT models. The latter predict a larger value for the KIE than measured and possible explanations for this are discussed.
- Shernyukov, Andrey V.,Genaev, Alexander M.,Salnikov, George E.,Shubin, Vyacheslav G.,Rzepa, Henry S.
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supporting information
p. 3781 - 3789
(2019/04/17)
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- Mechanistic studies of adamantylacetophenones with competing reaction pathways in solution and in the crystalline solid state
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Photochemical reactions in crystals occur under conditions of highly restricted molecular mobility such that only one product is generally obtained, even when there are many others that can be observed in the gas phase or in solution. A series of 2-(1-ada
- Hipwell, Vince M.,Garcia-Garibay, Miguel A.
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p. 11103 - 11113
(2019/09/30)
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- Dichloro-Cycloazatriphosphane: The Missing Link between N2P2 and P4 Ring Systems in the Systematic Development of NP Chemistry
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A dichloro-cycloazatriphosphane that incorporates a cyclic NP3 backbone could be synthesized using knowledge gained from the chemistry of N2P2 and P4 ring systems. It fills the gap between the congeneric compounds [ClP(μ-NR)]2 and [ClP(μ-PR)]2 (R=sterically demanding substituent), and thus contributes to the systematic development of nitrogen–phosphorus chemistry in general. The title compound was studied with respect to its formation via a labile aminodiphosphene, which readily underwent different rearrangement reactions depending on the solvent. All compounds were fully characterized by experimental and computational methods.
- Bresien, Jonas,Hinz, Alexander,Schulz, Axel,Suhrbier, Tim,Thomas, Max,Villinger, Alexander
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p. 14738 - 14742
(2017/10/12)
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- Functionalization of P4 using a Lewis acid stabilized bicyclo[1.1.0]tetraphosphabutane anion
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Reacting white phosphorus (P4) with sterically encumbered aryl lithium reagents (aryl=2,6-dimesitylphenyl or 2,4,6-tBu3C6H2) and B(C6F5)3 gives the unique, isolable Lewis acid st
- Borger, Jaap E.,Ehlers, Andreas W.,Lutz, Martin,Slootweg, J. Chris,Lammertsma, Koop
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supporting information
p. 12836 - 12839
(2016/02/18)
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- Carbenoid chain reactions: Substitutions by organolithium compounds at unactivated 1-chloro-1-alkenes
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The deceptively simple "cross-coupling" reactions Alk 2C=CA-Cl + RLi → Alk2C=CA-R + LiCl (A = H, D, or Cl) occur via an alkylidenecarbenoid chain mechanism in three steps without a transition metal catalyst. In the initiating step 1,
- Knorr, Rudolf,Pires, Claudio,Behringer, Claudia,Menke, Thomas,Freudenreich, Johannes,Rossmann, Eva C.,Boehrer, Petra
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p. 14845 - 14853
(2008/02/09)
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- Formation by SRN1 reactions and 1H N.M.R. properties of sterically encumbered 2,4,6-triaIkyIphenyl p-nitrobenzyl sulfides
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Sterically hindered p-nitrobenzylic chlorides (1) and (2) react with the sodium salts of 2,4,6-trialkylbenzenethiols (3a)-(5a) by the SRN1 reaction to give good yields of the corresponding p-nitrobenzylic aryl sulfides (6)-(10). For example, th
- Look, Kai,Norris, Robert K.
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p. 1077 - 1083
(2007/10/03)
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- The carbon - Lithium bond in monomeric aryllithiums: Dynamics of exchange, relaxation, and rotation
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Carbon-13 NMR line shape analysis of the lithium isotopomers of 2,4,6-tri-tert-butylphenyllithium monomer, 4, complexed to THF establishes that electric quadrupole induced relaxation of 7Li is responsible for partial averaging of 1J(
- Fraenkel, Gideon,Subramanian, Sheela,Chow, Albert
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p. 6300 - 6307
(2007/10/02)
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- REACTION OF A DIPHOSPHENE WITH VARIOUS HALOGENS
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Bis (2,4,6-tri-tert-butylphenyl)diphosphene reacts with various halogens to give the corresponding phosphonic dihalides, haloarene, and arene depending upon the halogen and solvent used.
- Yoshifuji, Masaaki,Shima, Ichiro,Shibayama, Katsuhiro,Inamoto, Naoki
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p. 411 - 414
(2007/10/02)
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- Chemistry of Sulfenic Acids. 3. Studies of Sterically Hindered Sulfenic Acids Using Flash Vacuum Pyrolysis
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Flash vacuum pyrolysis (FVP) of sulfoxides containing β-hydrogen atoms affords sulfenic acids (RSOH) in good concentration under conditions where they are stable.The application of this technique to the synthesis and study of sterically hindered sulfenic acids 12a-e is described.The principal or primary reaction of simple sulfenic acids prepared in this manner is dehydration to thiosulfinates 13 (eq 1).Steric inhibition to dehydration (eq 1) appears to only be of importance for 2-methyl-2-propanesulfenic acid (12a) which was trapped in good yield with methyl propiolate to afford 16a. 2,4,6-Tri-tert-butylbenzenesulfenic acid (12e) appears to be destabilized as a consequence of interaction between the SOH and adjacent tert-butyl groups.In the pyrolysis section of the apparatus, 12e decomposes to phenol 21 and aryl radical 22, which reacts further.Thermolysis of sulfoxides generates the sulfenic acids 12a-e in very low concentration at any one time.The products of sulfenic acids generated in this way result from secondary reactions of the corresponding thiosulfinates.
- Davis, Franklin A.,Jenkins, Robert H.,Rizvi, Syed Q. A.,Yocklovich, Steven G.
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p. 3467 - 3474
(2007/10/02)
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