14686-13-6Relevant articles and documents
New Procedure for Synthesis of 1,4-Dienes and Monoolefins via Methylcopper-Induced Cross-Coupling of Alkenylboranes with Organic Halides
Yatagai, Hidetaka
, p. 1640 - 1644 (1980)
The treatment of dialkenylchloroboranes (1) with 3 equiv of methylcopper at -30 to -40 deg C followed by addition of allylic halides gave 1,4-dienes.In the case of simple alkyl halides, the cross-coupling products were obtained with the aid of PhSLi or P(OEt)3.A similar cross-coupling reaction of alkenyl-9-BBN (13) with allylic halides was realized by the use of 1 equiv of methylcopper, while cross-coupling with alkyl halides failed even in the presence of ligands.Systems such as dialkenylchloroborane-methylcopper and alkenyl-9-BBN-methylcopper reacted withsubstituted allylic halides predominantly at a γ position.The regioselectivity of the former system was quite similar to that of the free alkenylcopper, while the regioselectivity of the latter system was greater than that of the free alkenylcopper.These results clearly indicate that the reactive intermediate of the latter system is an ate complex such as 19.
5-exo-trig Versus 6-endo-trig cyclization of Alk-5-enoyl radicals: The role of one-carbon ring expansion
Chatgilialoglu, Chryssostomos,Ferreri, Carla,Lucarini, Marco,Venturini, Alessandro,Zavitsas, Andreas A.
, p. 376 - 387 (1997)
Alk-5-enoyl radicals were made to cyclize in exo and endo modes to give the corresponding cycloketone radicals, which are related through one-carbon ring expansion. Relative kinetic data were determined for the ring closure of the 2-methylhept-5-enoyl radical generated by the reaction of the corresponding phenyl-seleno ester with Bu3SnH over the temperature range 233-323 K. The conversion to absolute rates provided Arrhenius expressions for the 5-exo-trig and 6-endo-trig cyclizations. Ab initio and semiempirical (AM1) calculations were performed on the hex-5-enoyl and hept-5-enoyl radicals, respectively, and the outcomes aided in the rationalization of the preexponential factors and activation energies. Both 1,5- and 1,6-ring closure occur via in a lower energy 'chairlike' transition state. The observed high regioselectivity is due to favorable entropic and enthalpic factors associated with the formation of the smaller ring. The stereoselectivity was higher in the 1,6-ring closure (70:30) than in the 1,5-ring closure (55:45), the trans isomer being predominant in both. For the one-carbon ring expansion studies, the radicals of interest were obtained by deoxygenation of suitable alcohols via the O-phenyl thiocarbonates with (TMS)3-SiH. The one-carbon ring expansion in the cyclopentanone series for the secondary alkyl radicals was studied over the temperature range 343-413 K by means of free-radical clock methodology and yielded the Arrhenius expression. The rate constant was 4.2 x 103 s-1 at room temperature and the reverse reaction (ring contraction) was found to be at least 10 times slower. Since the intermediacy of acyl radicals can be excluded, the reaction must occur via 3-membered cyclic intermediate radicals (or transition states).
C-F activation reactions at germylium ions: Dehydrofluorination of fluoralkanes
Braun, Thomas,Mei?ner, Gisa,Rachor, Simon G.,Talavera, Maria
supporting information, p. 4452 - 4455 (2020/05/13)
Reactions of the trityl cations with germanes afford the germylium ions [R3Ge][B(C6F5)4] (1a: R = Et, 1b: R = Ph, 1c: R = nBu). These compounds react with germane or fluorogermane to give polynuclear species, which are sources of the mononuclear ions, The latter convert with phosphines to yield the [R3Ge-PR3]+ (4a: R = Et, 4b: R = Ph) cations. Catalytic dehydrofluorination reactions were observed for the C-F bond activation of fluoroalkanes when using germanes as hydrogen source.
Kolbe Electrolysis of Biomass-Derived Fatty Acids Over Pt Nanocrystals in an Electrochemical Cell
Yuan, Gang,Wu, Chan,Zeng, Guorong,Niu, Xiaopo,Shen, Guoqiang,Wang, Li,Zhang, Xiangwen,Luque, Rafael,Wang, Qingfa
, p. 642 - 648 (2019/12/24)
Electrochemical valorization of non-food biomass-derived carboxylates into fuels is promising for the conversion, storage, and distribution of renewable electricity. Herein, we demonstrate that biofuels, hydrogen, and bicarbonate can be simultaneously produced in an electrochemical cell by one-step electrolysis of free fatty acids under ambient conditions on 3D self-supported ultralow Pt loading (2 wt %) electrode. The three valuable products can naturally separate from each other during the electrolysis in the alkaline aqueous solution. The experimental suggests that Pt(100) and Pt(110) are favorable for the production of non-Kolbe and Kolbe hydrocarbons, respectively. DFT calculation further clarifies the adsorption and stabilization of the reaction intermediates on Pt(100) and Pt(110).
Designing bifunctional alkene isomerization catalysts using predictive modelling
Landman, Iris R.,Paulson, Erik R.,Rheingold, Arnold L.,Grotjahn, Douglas B.,Rothenberg, Gadi
, p. 4842 - 4851 (2017/10/23)
Controlling the isomerization of alkenes is important for the manufacturing of fuel additives, fine-chemicals and pharmaceuticals. But even if isomerization seems to be a simple unimolecular process, the factors that govern catalyst performance are far from clear. Here we present a set of models that describe selectivity and activity, enabling the rational design and synthesis of alkene isomerization catalysts. The models are based on simple molecular descriptors, with a low computational cost, and are tested and validated on a set of eleven known Ru-imidazol-phosphine complexes and two new ones. Despite their simplicity, these models show good predictive power, with R2 values of 0.60-0.85. Using a combination of principal components analysis (PCA) and partial least squares (PLS) regression, we construct a "catalyst map", that captures trends in reactivity and selectivity as a function of electrostatic charge on the N? atom, EHOMO, polar surface area and the optimal mass substituents on P/distance Ru-P ratio. In addition to indicating "good regions" in the catalyst space, these models also give insight into mechanistic steps. For example, we find that the electrostatic charge on N?, EHOMO and polar surface area are crucial in the rate-limiting step, whereas the optimal mass of substituents on P/distance Ru-P is correlated with the product selectivity.
