1192-30-9Relevant articles and documents
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Garst,Barbas
, p. 3239,3241, 3244, 3245 (1974)
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Chemoenzymatic Halocyclization of γ,δ-Unsaturated Carboxylic Acids and Alcohols
Younes, Sabry H. H.,Tieves, Florian,Lan, Dongming,Wang, Yonghua,Süss, Philipp,Brundiek, Henrike,Wever, Ron,Hollmann, Frank
, (2019)
A chemoenzymatic method for the halocyclization of unsaturated alcohols and acids by using the robust V-dependent chloroperoxidase from Curvularia inaequalis (CiVCPO) as catalyst has been developed for the in situ generation of hypohalites. A broad range of halolactones and cyclic haloethers are formed with excellent performance of the biocatalyst.
X+ transfer from the halonium ions of adamantylideneadamantane to acceptor olefins. The possibility of chiral induction in the transfer process
Neverov, Alexei A.,Muise, Theresa L.,Brown
, p. 1844 - 1850 (1997)
The bromonium ion of adamantylideneadamantane (Ad=Ad-Br+) has been used to induce the bromocyclization of a 4-pentenyl glycoside (10) and a 5-hexenyl glycoside (11) in dichloroethane. The kinetics of these processes have been studied at 25°C in the presence of varying [Ad=Ad] and, in the case of the transfer to 10, in the presence of pentanol. The second-order rate constants for bromocyclization of these two alkenes are (1.04 ± 0.06) × 10-1 M-1 s-1 and (5.34 ± 0.2) × 10-2 M-1 s-1, respectively, and in no case does added Ad=Ad or pentanol alter the reaction rate. The kinetic behavior is interpreted in terms of cyclization occurring directly from a 1:1 complex of Ad=Ad-Br+ and 10 or 11. The chiral induction for the bromocyclization of 10 promoted by AdAd-Br+ was measured at 20% e.e., the (-)-(S)-tetrahydrofurfuryl bromide being the dominant stereoisomer. Ad=Ad molecules substituted at one of the homoallylic carbons by an axial methyl group (12), or by two methyl groups (axial and equatorial), were synthesized and the 1H NMR spectra of their bromonium ions is given. These materials are not stable for prolonged times at room temperature. A limited kinetic study of the reaction of 12-Br+ and 4-pentenol indicated that the Br+ transfer is 500 times faster than the comparable transfer from Ad=Ad-Br+ to 4-pentenol. The possibility of using these materials to induce chiral bromocyclization is discussed.
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.
Synthesis, structural characterization and catalytic activity of a multifunctional enzyme mimetic oxoperoxovanadium(v) complex
Si, Tapan K.,Paul, Shiv S.,Drew, Michael G. B.,Mukherjea, Kalyan K.
scheme or table, p. 5805 - 5815 (2012/06/15)
The synthesis and structural characterization of a novel oxoperoxovanadium(v) complex [VO(O2)(PAH)(phen)] containing the ligands 2-phenylacetohydroxamic acid (PAHH) and 1,10-phenanthroline (phen) has been accomplished. The oxoperoxovanadium(v) complex was found to mimic both vanadate-dependent haloperoxidase (VHPO) activity as well as nuclease activity through effective interaction with DNA. The complex is the first example of a structurally characterized stable oxoperoxovanadium(v) complex with a coordinated bi-dentate hydroximate moiety (-CONHO-) from 2-phenylacetohydroximate (PAH). The oxoperoxovanadium(v) complex has been used as catalyst for the peroxidative bromination reaction of some unsaturated alcohols (e.g. 4-pentene-1-ol, 1-octene-3-ol and 9-decene-1-ol) in the presence of H2O2 and KBr. The catalytic products have been characterized by GC-MS analysis and spectrophotometric methods. The DNA binding of this complex has been established with CT DNA whereas the DNA cleavage was demonstrated with plasmid DNA. The interactions of the complex with DNA have been monitored by electronic absorption and fluorescence emission spectroscopy. Viscometric measurements suggest that the compound is a DNA intercalator. The nuclease activity of this complex was confirmed by gel electrophoresis studies.
