Microwave-mediated Newman–Kwart rearrangement in water

Hoffmann, Ina; Schatz, J.

doi:10.1039/c6ra20676j

Cited by 6 publications

(5 citation statements)

References 44 publications

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“…The analytic data are in accordance with the literature. 30 (E)-S-(2-Methoxy-4-(prop-1-en-1-yl)phenyl) N,N-Dimethylcarbamothioate (14). Conversion: 49% (Condition A).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Lately a series of developments have attracted renewed attention to the NKR. − A Pd-catalyzed NKR was described where the rearrangement proceeds at 100 °C using catalytic Pd( t -Bu 3 P) 2 (Figure B) . Here, substrates with electron-withdrawing groups react faster than substrates with electron-donating groups, nonetheless high yields were obtained for both classes.…”

Section: Introductionmentioning

confidence: 99%

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Inverting the Selectivity of the Newman–Kwart Rearrangement via One Electron Oxidation at Room Temperature

et al. 2018

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The discovery that the Newman-Kwart rearrangement can be performed at room temperature by action of a simple and readily available oxidant, cerium ammonium nitrate, is described. The conditions give clean conversion when using electron-rich aromatic substrates, and the reactions are often quantitative. Computational studies support a reaction mechanism where the O-thiocarbamate is first oxidized to the radical cation, followed by nucleophilic attack by the ipso carbon of the aromatic system.

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“…The analytic data are in accordance with the literature. 30 (E)-S-(2-Methoxy-4-(prop-1-en-1-yl)phenyl) N,N-Dimethylcarbamothioate (14). Conversion: 49% (Condition A).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Inverting the Selectivity of the Newman–Kwart Rearrangement via One Electron Oxidation at Room Temperature

et al. 2018

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“…Since the appearance of the first reports in 1966, a number of studies have therefore dealt with the development of protocols having milder reaction conditions. Important parts of this development are the exploration of the microwave-assisted NKR, and of the use of a continuous flow reactor under supercritical conditions. , Other approaches are based on the use of catalysts in order to lower reaction temperatures. In some examples, the addition of catalytic amounts of BF 3 ·OEt 2 helped to lower the reaction temperature and to improve the yields, whereby the catalytic effect did not turn out to be general .…”

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confidence: 99%

An Electrocatalytic Newman–Kwart-type Rearrangement

et al. 2018

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An electrochemical approach toward rearrangement of O-aryl thiocarbamates to the corresponding S-aryl thiocarbamates is presented. The protocol requires only catalytic amounts of electric charge and allows for operation at room temperature. The electrolysis can be carried out with the simplest equipment, i.e., under galvanostatic conditions in an undivided cell. Furthermore, it is demonstrated that when the electrolysis is performed in a microflow reactor, almost quantitative yields can be achieved without using supporting electrolyte.

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“…One hurdle to exploring thiol-equipped MOF solids is the synthesis of the organic linkers. For example, the thiol group can be derived from the phenol group via the Newman–Kwart rearrangement, − but this usually involves harsh high-temperature conditions, e.g., 200 °C; the lower-temperature protocols, e.g., enabled by Pd or photocatalysts, − remain to be tested in linker synthesis. Serious drawbacks also exist in reductive − and nucleophilic , dealkylation of thioethers, as these treatments are often incompatible with the donor groups, e.g., carboxyl, for MOF construction.…”

Section: Resultsmentioning

confidence: 99%

A Thiol-Functionalized UiO-67-Type Porous Single Crystal: Filling in the Synthetic Gap

et al. 2018

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Thiol groups (−SH) offer versatile reactivity for functionalizing metal–organic frameworks, and yet thiol-equipped MOF solids remain underexplored due to synthetic challenges. Building on the recent breakthrough using benzyl mercaptan as the sulfur source and AlCl3 for uncovering the thiol function, we report on the thiol-equipped linker 3,3′-dimercaptobiphenyl-4,4′-dicarboxylic acid and its reaction with Zr(IV) ions to form a UiO-67-type MOF solid with distinct functionalities. The thiol-equipped UiO-67 scaffold shows substantial stability toward oxidation, e.g., it can be treated with 30% H2O2 to afford oxidation of the thiol to the strongly acidic sulfonic function while maintaining the ordered porous MOF structure. The thiol groups also effectively take up palladium(II) ions from solutions to allow for comparative studies on catalytic activities and to help elucidate how the spatial configuration of the thiol groups can be engineered to impact the performance of heterogeneous catalysis in the solid state. Comparative studies on the stability in the solventless (activated) state also help to highlight the steric factor in stabilizing UiO-67-type frameworks.

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Microwave-mediated Newman–Kwart rearrangement in water

Abstract: For the first time the unimolecular Newman–Kwart rearrangement is performed in pure water.

Cited by 6 publications

References 44 publications

Inverting the Selectivity of the Newman–Kwart Rearrangement via One Electron Oxidation at Room Temperature

Inverting the Selectivity of the Newman–Kwart Rearrangement via One Electron Oxidation at Room Temperature

An Electrocatalytic Newman–Kwart-type Rearrangement

A Thiol-Functionalized UiO-67-Type Porous Single Crystal: Filling in the Synthetic Gap

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