123485-24-5Relevant articles and documents
B2pin2-Mediated Palladium-Catalyzed Diacetoxylation of Aryl Alkenes with O2 as Oxygen Source and Sole Oxidant
Huang, Jiuzhong,Ouyang, Lu,Li, Jianxiao,Zheng, Jia,Yan, Wuxin,Wu, Wanqing,Jiang, Huanfeng
supporting information, p. 5090 - 5093 (2018/09/12)
A novel palladium-catalyzed alkene diacetoxylation with dioxygen (O2) as both the sole oxidant and oxygen source is developed, which was identified by 18O-isotope labeling studies. Control experiments suggested that bis(pinacolato)diboron (B2pin2) played a dominant intermediary role in the formation of a C-O bond. This method performed good functional group tolerance with moderate to excellent yields, which could be successfully applied to the late-stage modification of natural products. Furthermore, an atmospheric pressure of dioxygen enhances the practicability of the protocol.
Mechanistically Driven Development of an Iron Catalyst for Selective Syn-Dihydroxylation of Alkenes with Aqueous Hydrogen Peroxide
Borrell, Margarida,Costas, Miquel
supporting information, p. 12821 - 12829 (2017/09/25)
Product release is the rate-determining step in the arene syn-dihydroxylation reaction taking place at Rieske oxygenase enzymes and is regarded as a difficult problem to be resolved in the design of iron catalysts for olefin syn-dihydroxylation with potential utility in organic synthesis. Toward this end, in this work a novel catalyst bearing a sterically encumbered tetradentate ligand based in the tpa (tpa = tris(2-methylpyridyl)amine) scaffold, [FeII(CF3SO3)2(5-tips3tpa)], 1 has been designed. The steric demand of the ligand was envisioned as a key element to support a high catalytic activity by isolating the metal center, preventing bimolecular decomposition paths and facilitating product release. In synergistic combination with a Lewis acid that helps sequestering the product, 1 provides good to excellent yields of diol products (up to 97% isolated yield), in short reaction times under mild experimental conditions using a slight excess (1.5 equiv) of aqueous hydrogen peroxide, from the oxidation of a broad range of olefins. Predictable site selective syn-dihydroxylation of diolefins is shown. The encumbered nature of the ligand also provides a unique tool that has been used in combination with isotopic analysis to define the nature of the active species and the mechanism of activation of H2O2. Furthermore, 1 is shown to be a competent synthetic tool for preparing O-labeled diols using water as oxygen source.
Vicinal Difunctionalization of Alkenes under Iodine(III) Catalysis involving Lewis Base Adducts
Aertker, Kristina,Rama, Raquel J.,Opalach, Julita,Mu?iz, Kilian
supporting information, p. 1290 - 1294 (2017/04/18)
The influence of a 2-pyridinyl substituent on the catalytic performance of aryl iodides as catalyst in iodine(III) chemistry was explored. An efficient Lewis base adduct between the pyridine nitrogen and the electrophilic iodine(III) center was identified and confirmed by X-ray analysis. This arrangement was shown to generate a kinetically competent superior catalyst structure for the catalytic dioxygenation of alkenes. It introduces the concept of Lewis base adduct formation as a kinetic factor in iodine(I/III) catalysis. (Figure presented.).
Synthesis of Optically Active 1-Phenyl-1,2-propanediol by Use of Baker's Yeast
Takeshita, Mitsuhiro,Sato, Takumi
, p. 1085 - 1086 (2007/10/02)
Reduction of 1-phenyl-1,2-propanedione with baker's yeast afforded (1R,2S)-1-phenyl-1,2-propanediol in high chemical and optical yield. (1R,2S)-, (1R,2R)- and (1S,2S)-1,2-propanediols were also prepared via (1R)- or (2S)-α-ketols, which were obtained as intermediates of the above reaction.
The Role of Copper(II) Salts in the Oxidation of Aryl-substituted Alkenes by Peroxydisulphate Anion
Dobson, Peter,Norman, Julie A.,Thomas, C. Barry
, p. 1209 - 1214 (2007/10/02)
The effect of copper(II) ions on the oxidation, in acetic acid, of aryl-substituted alkenes by peroxydisulphate anion has been investigated.In the presence of the metal ions an electron-transfer process operates akin to that identified in the oxidation of alkenes by other one-electron oxidants.It is suggested that the electron-transfer agent is copper(III) and that the resultant alkene radical-cation is converted into hydroxy acetates in good yield.S2O8(2-) alone decomposes more slowly to SO4(*-) which undergoes radical addition to the alkene leading ultimately to diacetates.The presence of sodium acetate in the system reduces considerably the conversion of alkene as a result, it is suggested, of competitive oxidation of the acetate anion.
Manganese(III)-Mediated γ-Lactone Annulation
Fristad, William E.,Peterson, John R.
, p. 10 - 18 (2007/10/02)
The annulation of a γ-lactone ring onto an alkene by manganese(III) acetate oxidation of acetic acid was investigated.The regioselectivity of addition to unsymmetrically substituted alkenes is reported along with the stereoselectivity of addition to various acyclic and cyclic alkenes.Alkenes with ionization potentials above 8.2 eV were found to react in good yield.The role of acetic anhydride in these reactions was studied, and it was shown to be oxidized faster than acetic acid and also led to different products.The fate of oxidized acetic acid or anhydridein the absence of suitable acceptor molecule has also been quantitatively identified.The relationship of enolizability, or C-H acidity, of the carboxylic acid being oxidized was established quantitatively.
Electron-transfer Processes: Oxidation of α- and β-Alkenylbenzenes by Peroxydisulphate in Acetic Acid
Citterio, Attilio,Arnoldi, Claudio,Giordano, Claudio,Castaldi, Grasiano
, p. 891 - 896 (2007/10/02)
Oxidation of α- and β-unsaturated alkylbenzenes by peroxydisulphate in acetic acid gives side-chain acetoxylation with formation of the corresponding glycol diacetates and compounds (10), respectively.The reaction is catalysed by transition-metal salts, among which cupric acetate gives the best results.Generally, electron-releasing substituents on the benzene ring increase the yield and improve the selectivity.The same substrates are oxidized in water under Ag+ catalysis to the corresponding aldehydes.The different behaviour in the two solvents is ascribed to the difference in reactivity between the primary oxidation products and the starting olefin, whereas the initial oxidation step is suggested to occur in both cases via an electron-transfer process from the olefin to the sulphate radical anion.
