34293-21-5Relevant academic research and scientific papers
Beyond Takai's Olefination Reagent: Persistent Dehalogenation Emerges in a Chromium(III)-μ3-Methylidyne Complex
Anwander, Reiner,Langmann, Jan,Maichle-M?ssmer, C?cilia,Scherer, Wolfgang,Trzmiel, Simon,Werner, Daniel
supporting information, p. 20049 - 20054 (2021/08/06)
Reaction of CHI3 with six equivalents of CrCl2 in THF at low temperatures affords [Cr3Cl3(μ2-Cl)3(μ3-CH)(thf)6] as the first isolable high-yield CrIII μ3-methylidyne complex. Substitution of the terminal chlorido ligands via salt metathesis with alkali-metal cyclopentadienides generates isostructural half-sandwich chromium(III)-μ3-methylidynes [CpR3Cr3(μ2-Cl)3(μ3-CH)] (CpR=C5H5, C5Me5, C5H4SiMe3). Side and decomposition products of the Cl/CpR exchange reactions were identified and structurally characterized for [Cr4(μ2-Cl)4(μ2-I)2(μ4-O)(thf)4] and [(η5-C5H4SiMe3)CrCl(μ2-Cl)2Li(thf)2]. The Cl/CpR exchange drastically changed the ambient-temperature effective magnetic moment μeff from 9.30/9.11 μB (solution/solid) to 3.63/4.32 μB (CpR=C5Me5). Reactions of [Cr3Cl3(μ2-Cl)3(μ3-CH)(thf)6] with aldehydes and ketones produce intricate mixtures of species through oxy/methylidyne exchange, which were partially identified as radical recombination products through GC/MS analysis and 1H NMR spectroscopy.
Oxovanadium(v)-catalyzed deoxygenative homocoupling reaction of alcohols
Sakuramoto, Takashi,Donaka, Yosuke,Tobisu, Mamoru,Moriuchi, Toshiyuki
, p. 17571 - 17576 (2019/11/25)
Oxovanadium(v)-catalyzed transformation of alcohols in the presence of hydrazine derivatives was demonstrated. The direct hydrazination reaction of 1,3-diphenylprop-2-en-1-ol with 1,1-diphenylhydrazine in the presence of VO(OSiPh3)3 as a catalyst and MS3A as a dehydrating reagent proceeded to afford the corresponding hydrazination product. On the contrary, the utilization of 1,1-dimethylhydrazine instead of 1,1-diphenylhydrazine was found to induce the deoxygenative homocoupling reaction of the allyl alcohol to give the corresponding 1,5-diene as a major product. In addition to the deoxygenative homocoupling product, the allyl amine into which aniline was introduced was also obtained by using 1,2-diphenylhydrazine in the reaction of 1,3-diphenyl-2-methylprop-2-en-1-ol. Oxovanadium(v)-catalyzed deoxygenative homocoupling reaction of benzyl alcohols could also be performed in the presence of 1,1-dimethylhydrazine.
Visible Light Photocatalytic Reduction of O-Thiocarbamates: Development of a Tin-Free Barton-McCombie Deoxygenation Reaction
Chenneberg, Ludwig,Baralle, Alexandre,Daniel, Marion,Fensterbank, Louis,Goddard, Jean-Philippe,Ollivier, Cyril
supporting information, p. 2756 - 2762 (2016/02/19)
The Barton-McCombie deoxygenation is one of the most important transformations in the toolbox of organic chemists which has been the subject of a number of methodological developments. In this study, we report a photocatalyzed redox deoxygenation of secondary and tertiary alcohols from thiocarbamate precursors under visible light activation. The iridium complex Ir(ppy)3 proved to be the most efficient catalyst in the presence of Hünig's base as sacrifial electron donor. A mechanistic investigation is presented based on fluorescence quenching experiments and cyclic voltammetry.
A highly efficient, metal-free and convenient diarylallyl ether/ thioether formation via oxidative c-h activation
Li, Yan,Bao, Weiliang
supporting information; body text, p. 865 - 868 (2009/11/30)
A metal free highly efficient and concise oxidative-coupling ether formation between 1,3-diarylallylic sp3 C-H and aliphatic alcohols promoted by 2,3-dichloro-5,6-dicyanoquinone (DDQ) is reported. This system is also applied to form C-S bonds f
A non-cope among the cope rearrangements of 1,3,4,6-tetraphenylhexa-1,5- dienes
Doering,Birladeanu, Ludmila,Sarma, Keshab,Blaschke,Scheidemantel, Ursula,Boese,Benet-Bucholz, Jordi,Klaerner,Gehrke, Jan-Stephan,Zimny, Bernd Ulrich,Sustmann,Korth, Hans-Gert
, p. 193 - 203 (2007/10/03)
The set of 1,3,4,6-tetraphenylhexa-1,5-dienes (1) represents a perturbation of Cope's rearrangement by four radical-stabilizing phenyl groups all positioned to drive the transition region toward the homolytic- colligative end of the mechanistic spectrum. The appearance of (Z)-isomers being suppressed thermodynamically by a steric interaction of +2.6 kcal mol- 1 per cis double bond, an equilibration that is stereochemically not of any Cope type, emerges as the predominant reaction. It is an interconversion of rac-(E,E)-1 and meso-(E,E)-1 (48:52; 77.3-115.3 °C) with the following values of the enthalpy, entropy, and volume of activation: ΔH(+) = 30.7 ± 0.2 kcal mol-1, ΔS(+) = +2.1 ± 0.4 cal mol-1 K-1, and ΔV(+) = +13.5 ± 0.1 cm-3 mol-1, respectively. Structures have been established by X- ray crystallographic analysis; a possible relationship between dihedral angle and bond lengths in the styrene portions is proposed. The entropy of activation is incompatible with a chair or boat Cope rearrangement; the volume of activation is neither low enough for a pericyclic Cope ('concerted') mechanism nor high enough for a homolytic-colligative mechanism involving full dissociation as the rate-determining step. Trapping and a crossover experiment give some but only partial support to the intermediacy of free radicals. At higher temperatures, however, electron spin resonance experiments demonstrate an equilibrium with kinetically free (E,E)-1,3- diphenylallyl radicals. These observations are rationalized in terms of geometric reorganization within the confines of a 'cage'. Resolution by chiral chromatography of rac-(E,E)-1 allows recognition of a fast racemization (40-65 °C), of which ΔH(+) (21.3 ± 0.1 kcal mol-1), DS(+) (-13.2 ± 0.3 cal mol-1 K-1), and ΔV(+) (-7.4 ± 0.4 cm-3 mol-1) are consistent with a pericyclic Cope rearrangement. Enriched (Z)-isomers undergo Cope rearrangements in accord with the known influence of axiality and the chair/boat alternative on the energy of the transition region.
