Radical-Cation Catalysis in the Synthesis of Diphenylmethanes via the Dealkylative Coupling of Benzylic Ethers
摘要:
The dealkylative coupling of benzyl alkyl ethers (ArCH(2)OR) to yield the corresponding diarylmethanes (ArCH2Ar) together with dialkoxymethane (ROCH(2)OR) is catalyzed by small amounts of 1-electron oxidants (such as aromatic cation radicals, NO+, etc.) or py an equivalent electrochemical (anodic) method. The catalytic method is successfully employed for the facile synthesis of a novel macrocyclic crown ether 18 that contains a diarylmethane linkage. On the basis of the spectral observation of the radical cation ArCH(2)OR(.+) and the excellent catalytic efficiency with turnover numbers in excess of 10(2), an electron-transfer and an alternative electrophilic chain mechanism are discussed for the dealkylative coupling process.
Radical-Cation Catalysis in the Synthesis of Diphenylmethanes via the Dealkylative Coupling of Benzylic Ethers
摘要:
The dealkylative coupling of benzyl alkyl ethers (ArCH(2)OR) to yield the corresponding diarylmethanes (ArCH2Ar) together with dialkoxymethane (ROCH(2)OR) is catalyzed by small amounts of 1-electron oxidants (such as aromatic cation radicals, NO+, etc.) or py an equivalent electrochemical (anodic) method. The catalytic method is successfully employed for the facile synthesis of a novel macrocyclic crown ether 18 that contains a diarylmethane linkage. On the basis of the spectral observation of the radical cation ArCH(2)OR(.+) and the excellent catalytic efficiency with turnover numbers in excess of 10(2), an electron-transfer and an alternative electrophilic chain mechanism are discussed for the dealkylative coupling process.
METHOD AND DEVICE FOR ELECTRONICALLY CONTROLLING THE PH OF A SOLUTION
申请人:Robert Bosch GmbH
公开号:EP3708673A1
公开(公告)日:2020-09-16
Device and methods for use in a biosensor comprising a multisite array of test sites, the device and methods being useful for modulating the binding interactions between a (biomolecular) probe or detection agent and an analyte of interest by modulating the pH or ionic gradient near the electrodes in such biosensor. An electrochemically active agent that is suitable for use in biological buffers for changing the pH of the biological buffers. Method for changing the pH of biological buffers using the electrochemically active agents. The methods of modulating the binding interactions provided in a biosensor, analytic methods for more accurately controlling and measuring the pH or ionic gradient near the electrodes in such biosensor, and analytic methods for more accurately measuring an analyte of interest in a biological sample.
Acid Catalysis vs. Electron-Transfer Catalysis via Organic Cations or Cation-Radicals as the Reactive Intermediate. Are These Distinctive Mechanisms?
作者:Rajendra Rathore、Jay K. Kochi、Augusto Canavesi、Larry L. Miller、Giovanni V. Sebastiani、George W. Francis、József Szúnyog、Bengt Långström
DOI:10.3891/acta.chem.scand.52-0114
日期:——
Proton transfer to aromatic and olefinic donors (D) lends to the facile interchange of transient carbocations (DH+) and cation-radical (D+.). The same types of cation and cation-radical are reactive intermediates in the acid catalysis and the electron-transfer catalysis of such organic transformations as benzylic coupling, epoxide.-pinacol rearrangements and cis-trans isomerization of stilbenes when they are both carried out under otherwise identical reaction conditions, However, the rapid exchange of diamagnetic cations and paramagnetic cation-radicals blurs the traditional view of sepal ate electrophilic and homolytic processes, and rigorous experimental evidence is required to establish whether acid catalysis and electron-transfer catalysis actually represent distinct mechanistic categories.
Radical-Cation Catalysis in the Synthesis of Diphenylmethanes via the Dealkylative Coupling of Benzylic Ethers
作者:Rajendra Rathore、Jay K. Kochi
DOI:10.1021/jo00128a020
日期:1995.11
The dealkylative coupling of benzyl alkyl ethers (ArCH(2)OR) to yield the corresponding diarylmethanes (ArCH2Ar) together with dialkoxymethane (ROCH(2)OR) is catalyzed by small amounts of 1-electron oxidants (such as aromatic cation radicals, NO+, etc.) or py an equivalent electrochemical (anodic) method. The catalytic method is successfully employed for the facile synthesis of a novel macrocyclic crown ether 18 that contains a diarylmethane linkage. On the basis of the spectral observation of the radical cation ArCH(2)OR(.+) and the excellent catalytic efficiency with turnover numbers in excess of 10(2), an electron-transfer and an alternative electrophilic chain mechanism are discussed for the dealkylative coupling process.