28304-67-8Relevant articles and documents
Mechanistic investigation of the isomerization of 5-vinyl-2-norbornene
Kim, Hoon Sik,Lee, So Young,Lee, Hyunjoo,Bae, Jin Young,Park, Sang Joon,Cheong, Minserk,Lee, Je Seung,Lee, Chang-Ha
, p. 911 - 914 (2006)
The isomerization reaction of 5-vinyl-2-norbornene (VNB) to 5-ethylidene-2-norbornene (ENB) has been performed using a catalytic system consisting of an alkali metal hydride and an amine. Among various amines tested, only aliphatic 1,2-diamines exhibited the activity for the isomerization. The isomerization was also affected by the alkali metal hydride employed. The activity of the alkali metal hydride increased with the increasing size of alkali metal: KH > NaH > LiH. A series of electron paramagnetic resonance (EPR) and UV-vis experiments on the active species suggest that the isomerization of VNB proceeds through a radical mechanism.
α-Methylene-β-lactones as novel allene equivalents: Regioselective [4 +2] cycloaddition and stereoselective decarboxylation for the introduction of exo-alkylidene functionalities
Adam, Waldemar,Hasemann, Ludwig
, p. 7033 - 7036 (1991)
β-Lactone-capped allene dienophiles afforded with cyclopentadiene spiro-β-lactone as [4+2] cycloadducts, which on thermal decarboxylation gave regio- and stereoselectively E-5-alkylidene 2-norbornenes.
A General Strategy for Open-Flask Alkene Isomerization by Ruthenium Hydride Complexes with Non-Redox Metal Salts
Lv, Zhanao,Chen, Zhuqi,Hu, Yue,Zheng, Wenrui,Wang, Haibin,Mo, Wanling,Yin, Guochuan
, p. 3849 - 3859 (2017/09/18)
A homogenous metal hydride (M?H) catalyst for isomerization normally requires rigorous air-free techniques. Here, we demonstrate a highly efficient protocol in which simple non-redox metal ions as Lewis acids can promote olefin isomerization dramatically with a commercially available RuH2(CO)(PPh3)3 complex in an open-flask system. Isomerization can be accomplished within a short time, and a satisfactory selectivity for different types of unsaturated compounds can be obtained. Meanwhile, an excellent turnover number up to 17208 was achieved under air, and open-flask gram-scale experiments further demonstrated the efficiency of the RuH2(CO)(PPh3)3/non-redox-metals system. We used FTIR spectroscopy, GC–MS, NMR spectroscopy and kinetics studies to evidence that in the sluggish RuH2(CO)(PPh3)3 catalyst, bloated PPh3 ligands cause steric hindrance for the coordination of the free alkene. Alternatively, the addition of non-redox metal ions could induce the dissociation of the PPh3 ligand to offer unoccupied coordination sites for the alkene and to form the Mg-bridged adduct OC?Ru?H2?Mg2+ as the highly active species, which benefited the isomerization significantly through the metal hydride addition–elimination pathway. Finally, this strategy was demonstrated as an impactful approach for hydride catalysts of other transition metals such as Os.
Superbase Character of Alumina loaded with Potassium by Impregnation from Ammoniacal Solution
Baba, Toshihide,Handa, Haruhisa,Ono, Yoshio
, p. 187 - 192 (2007/10/02)
Al2O3 has been loaded with potassium by impregnation from an ammoniacal solution and heated under vacuum at 573 K.The resulting catalyst showed extremely high catalytic activity for the isomerization of alkenes.These catalysts had much greater activity than that of Al2O3 loaded with alkali metals by vapour deposition.The isomerization, over K(NH3)/Al2O3, of pent-1-ene to pent-2-ene gave a 98percent yield in 6 min at 201 K.The temperature-programmed desorption and IR spectra of Al2O3 after impregnation indicated that the metal amide-like species formed on the alumina is a catalytically active species.Al2O3 loaded with KNH2 was found to be more active than K(NH3)/Al2O3 for the isomerization of 2,3-dimethylbut-1-ene.The basic strength of these catalysts was estimated to be at least H- = 37.
Isomerization of 5-Vinyl-8,9,10-trinorborn-2-ene catalyzed by N,N'-Ethylenebis(salicylideneiminato)cobalt(II) - Triethylaluminium system.
Samnani, Prakash B.,Bhattacharya, Pabitra Krishna,Pillai, S. Muthukumaru,Satish, Sheo
, p. 1868 - 1890 (2007/10/02)
Isomerization of 5-vinyl-8,9,10-trinorborn-2-ene (1) ti 5-ethylidene-8,9,10-trinorborn-2-ene (2) has been studied using Co(II) - (salen) - AlEt3 as catalyst in the temperature range 25-100 deg C.It is observed that the nature of the anionic Schiff base or Mannich base ligand does not affect the catalytic activity.However the use of ligands like PPh3, pyridine and imidazole with Co(II)(salen improves the activity of the catalyst.The selectivity to 2 and turnover of the cobalt catalyst system are found to be dependent on the Co(II)(salen) : 1 and Co(II)(salen) : AlEt3ratios and reaction temperature.Conversions of 1 vary from 14-64percent with a maximum selectivity of 100percent for 2.Based on UV-Vis, EPR, Cv and catalytic studies a probable mechanism is proposed for the isomerization of 1.
α-Methylene β-Lactones as Masked Allenes and Allene Equivalents: Some Selected Chemical Transformations
Adam, Waldemar,Albert, Rainer,Hasemann, Ludwig,Nava Salgado, Victor O.,Nestler, Bernd,et al.
, p. 5782 - 5785 (2007/10/02)
Selective chemical transformations have been performed on a number of α-methylene β-lactones to illustrate that these highly functionalized heterocycles serve as useful building blocks in organic synthesis.Thus, thermal decarboxylation of these "masked al
Preparation of New Solid Superbase and Its Catalityc Activity
Suzukamo, Gohfu,Fukao, Masami,Minobe, Masao
, p. 585 - 588 (2007/10/02)
A solid superbase whose basicity (H-) was higher than 37 was prepared by the successive treatment of γ-alumina with sodium hydroxyde and sodium at 280-350 deg C under nitrogen.The base was highly effective in the catalytic isomerization of 5-vinylbicyclohept-2-ene to 5-ethylidenebicyclohept-2-ene.
