824-60-2Relevant articles and documents
Bis-selenonium Cations as Bidentate Chalcogen Bond Donors in Catalysis
He, Xinxin,Wang, Xinyan,Tse, Ying-Lung Steve,Ke, Zhihai,Yeung, Ying-Yeung
, p. 12632 - 12642 (2021/10/21)
Lewis acids are frequently employed in catalysis but they often suffer from high moisture sensitivity. In many reactions, catalysts are deactivated because of the problem that strong Lewis acids also bond to the products. In this research, hydrolytically stable bidentate Lewis acid catalysts derived from selenonium dicationic centers have been developed. The bis-selenonium catalysts are employed in the activation of imine and carbonyl groups in various transformations with good yields and selectivity. Lewis acidity of the bis-selenonium salts was found to be stronger than that of the monoselenonium systems, attributed to the synergistic effect of the two cationic selenonium centers. In addition, the bis-selenonium catalysts are not inhibited by strong bases or moisture.
The charge-assisted hydrogen-bonded organic framework (CAHOF) self-assembled from the conjugated acid of tetrakis(4-aminophenyl)methane and 2,6-naphthalenedisulfonate as a new class of recyclable Br?nsted acid catalysts
Belokon, Yuri N.,Dmitrienko, Artem O.,Gak, Alexander S.,Gerasimov, Igor S.,Kuznetsova, Svetlana A.,Larionov, Vladimir A.,Li, Han,Medvedev, Michael G.,Nelyubina, Yulia V.,North, Michael,Saghyan, Ashot S.,Smol'yakov, Alexander F.,Zhereb, Vladimir P.
supporting information, p. 1124 - 1134 (2020/07/10)
The acid–base neutralization reaction of commercially available disodium 2,6-naphthalenedisulfonate (NDS, 2 equivalents) and the tetrahydrochloride salt of tetrakis(4-aminophenyl)methane (TAPM, 1 equivalent) in water gave a novel three-dimensional charge-assisted hydrogen-bonded framework (CAHOF, F-1). The framework F-1 was characterized by X-ray diffraction, TGA, elemental analysis, and 1H NMR spectroscopy. The framework was supported by hydrogen bonds between the sulfonate anions and the ammonium cations of NDS and protonated TAPM moieties, respectively. The CAHOF material functioned as a new type of catalytically active Br?nsted acid in a series of reactions, including the ring opening of epoxides by water and alcohols. A Diels–Alder reaction between cyclopentadiene and methyl vinyl ketone was also catalyzed by F-1 in heptane. Depending on the polarity of the solvent mixture, the CAHOF F-1 could function as a purely heterogeneous catalyst or partly dissociate, providing some dissolved F-1 as the real catalyst. In all cases, the catalyst could easily be recovered and recycled.
Stereoselectivity in a series of 7-alkylbicyclo[3.2.0]hept-2-enes: Experimental and computational perspectives
Leber, Phyllis,Kidder, Katherine,Viray, Don,Dietrich-Peterson, Eric,Fang, Yuan,Davis, Alexander
, (2018/08/03)
Rate constants for overall decomposition (kd) for a series of exo-7-alkylbicyclo[3.2.0]hept-2-enes are relatively invariant. For the alkyl substituents ethyl, propyl, butyl, isopropyl, and t-butyl, the ratio of the rate constant for [1,3] sigmatropic rearrangement to the rate constant for fragmentation, k13/kf, is significantly lower than k13/kf?=?150 observed for exo-7-methylbicyclo[3.2.0]hept-2-ene. Regardless of the size and mass of the alkyl group, the stereoselectivity of the [1,3] carbon migration appears to be quite stable at 80% to 89% suprafacial inversion (si), an observation consistent with conservation of angular momentum but not conservation of orbital symmetry. This global result comports with the phenomenon of “dynamic matching” espoused by Carpenter and collaborators for [1,3] sigmatropic rearrangements in general.
