59-48-3Relevant articles and documents
Oxidation of indole with CPO and GOx immobilized on mesoporous molecular sieves
Jung, Dirk,Hartmann, Martin
, p. 378 - 383 (2010)
Green chemistry and environmentally benign reaction engineering play an important role for future industrial processes. It is expected that the number of chemical reactions carried out via enzymatic catalysis will increase strongly. To achieve this aim, stable (viz. leaching and deactivation is prevented) heterogeneous biocatalysts are required. In this study, cross-linked enzyme aggregates of chloroperoxidase were grown in large-pore mesocellular foams (MCF). By changing the various synthesis parameters, the specific activity and the effective activity (viz. the enzyme activity units per mmol of adsorbed enzyme) are improved. The resulting biocatalysts composed of cross-linked chloroperoxidase and cross-linked glucose oxidase were tested in the oxidation of indole. The catalytic test under continuous operation conditions in a fixed-bed reactor confirmed that the cross-linked enzymes are less prone to leaching compared to the physically adsorbed enzymes in the pores of MCF or SBA-15.
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Gassmann,van Bergen
, p. 2718 (1973)
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Paramagnetic nuclear magnetic resonance relaxation and molecular mechanics studies of the chloroperoxidase-indole complex: Insights into the mechanism of chloroperoxidase-catalyzed regioselective oxidation of indole
Zhang, Rui,He, Qinghao,Chatfield, David,Wang, Xiaotang
, p. 3688 - 3701 (2013)
To unravel the mechanism of chloroperoxidase (CPO)-catalyzed regioselective oxidation of indole, we studied the structure of the CPO-indole complex using nuclear magnetic resonance (NMR) relaxation measurements and computational techniques. The dissociation constant (KD) of the CPO-indole complex was calculated to be approximately 21 mM. The distances (r) between protons of indole and the heme iron calculated via NMR relaxation measurements and molecular docking revealed that the pyrrole ring of indole is oriented toward the heme with its 2-H pointing directly at the heme iron. Both KD and r values are independent of pH in the range of 3.0-6.5. The stability and structure of the CPO-indole complex are also independent of the concentration of chloride or iodide ion. Molecular docking suggests the formation of a hydrogen bond between the NH group of indole and the carboxyl O of Glu 183 in the binding of indole to CPO. Simulated annealing of the CPO-indole complex using r values from NMR experiments as distance restraints reveals that the van der Waals interactions were much stronger than the Coulomb interactions in the binding of indole to CPO, indicating that the association of indole with CPO is primarily governed by hydrophobic rather than electrostatic interactions. This work provides the first experimental and theoretical evidence of the long-sought mechanism that leads to the "unexpected" regioselectivity of the CPO-catalyzed oxidation of indole. The structure of the CPO-indole complex will serve as a lighthouse in guiding the design of CPO mutants with tailor-made activities for biotechnological applications.
Transition-metal-catalyzed electrophilic activation of 1,1-difluoro-1- alkenes: Oxindole synthesis via intramolecular amination
Tanabe, Hiroyuki,Ichikawa, Junji
, p. 248 - 249 (2010)
In the presence of a catalytic amount of palladium(II) chloride, β,β-difluorostyrenes bearing a sulfonamido group at the ortho position were treated with trimethylsilyl trifluoro-methanesulfonate to afford oxindoles in high yield. The reactions proceeded via 5-endo-trig cyclization, hydrolysis, and desulfonylation. This sequence allowed the transformation of difluorostyrenes into free oxindoles in a one-pot operation.
Fenton chemistry enables the catalytic oxidative rearrangement of indoles using hydrogen peroxide
Zhao, Guodong,Liang, Lixin,Wang, Eryu,Lou, Shaoyan,Qi, Rui,Tong, Rongbiao
supporting information, p. 2300 - 2307 (2021/04/12)
Oxidative rearrangement of indoles is an important transformation to yield 2-oxindoles and spirooxindoles, which are present in many pharmaceutical agents and bioactive natural products. Previous oxidation methods show either broad applicability or greenness but rarely achieve both. Reported is the discovery of Fenton chemistry-enabled green catalytic oxidative rearrangement of indoles, which has wide substrate scope (42 examples) and greenness (water as the only stoichiometric byproduct) at the same time. Detailed mechanistic studies revealed that the Fenton chemistry generated hydroxyl radicals that further oxidize bromide to reactive brominating species (RBS: bromine or hypobromous acid). Thisin situgenerated RBS is the real catalyst for the oxidative rearrangement. Importantly, the RBS is generated under neutral conditions, which addresses a long-lasting problem of many haloperoxidase mimics that require a strong acid for the oxidation of bromide with hydrogen peroxide. It is expected that this new catalytic Fenton-halide system will find wide applications in organic synthesis.
A novel methodology for the efficient synthesis of 3-monohalooxindoles by acidolysis of 3-phosphate-substituted oxindoles with haloid acids
Huang, Tiao,Kong, Dulin,Li, Yue,Liu, Li,Wu, Mingshu
, p. 2321 - 2328 (2021/09/22)
A novel method for the synthesis of 3-monohalooxindoles by acidolysis of isatin-derived 3-phosphate-substituted oxindoles with haloid acids was developed. This synthetic strategy involved the preparation of 3-phosphate-substituted oxindole intermediates and SN1 reactions with haloid acids. This new procedure features mild reaction conditions, simple operation, good yield, readily available and inexpensive starting materials, and gram-scalability.