613-62-7Relevant articles and documents
Selective O -alkylation of 2-naphthol using phosphonium-based ionic liquid as the phase transfer catalyst
Yadav, Ganapati D.,Tekale, Smruti P.
, p. 722 - 727 (2010)
The selective preparation of O-alkylated aromatic products from substituted phenol and naphthols is challenging. The O-alkylation of 2-naphthol with benzyl chloride has been studied in this work using phosphonium-based ionic liquids as catalysts such as trihexyl(tetradecyl)phosphonium chloride (THTDPC), trihexyl(tetradecyl)phosphonium bromide (THTDPB), trihexyl(tetradecyl) phosphonium decanoate (THTDPD), and trihexyl(tetradecyl)phosphonium hexafluorophosphate (THTDPH). This is a liquid-liquid phase-transfer-catalysed reaction with reuse of catalyst. The effects of various parameters such as agitation speed, various phosphonium-based ionic liquids, phase volume ratio, catalyst concentration, NaOH concentration, mole ratio of starting materials, and temperature were studied systematically to understand the conversion patterns and the selectivity of the desired product. A mechanism of the reaction and a kinetic model are proposed.
Photocatalytic Reductive C-O Bond Cleavage of Alkyl Aryl Ethers by Using Carbazole Catalysts with Cesium Carbonate
Yabuta, Tatsushi,Hayashi, Masahiko,Matsubara, Ryosuke
, p. 2545 - 2555 (2021/02/01)
Methods to activate the relatively stable ether C-O bonds and convert them to other functional groups are desirable. One-electron reduction of ethers is a potentially promising route to cleave the C-O bond. However, owing to the highly negative redox potential of alkyl aryl ethers (Ered -2.6 V vs SCE), this mode of ether C-O bond activation is challenging. Herein, we report the visible-light-induced photocatalytic cleavage of the alkyl aryl ether C-O bond using a carbazole-based organic photocatalyst (PC). Both benzylic and non-benzylic aryl ethers underwent C-O bond cleavage to form the corresponding phenol products. Addition of Cs2CO3 was beneficial, especially in reactions using a N-H carbazole PC. The reaction was proposed to occur via single-electron transfer (SET) from the excited-state carbazole to the substrate ether. Interaction of the N-H carbazole PC with Cs2CO3 via hydrogen bonding exists, which enables a deprotonation-assisted electron-transfer mechanism to operate. In addition, the Lewis acidic Cs cation interacts with the substrate alkyl aryl ether to activate it as an electron acceptor. The high reducing ability of the carbazole combined with the beneficial effects of Cs2CO3 made this otherwise formidable SET event possible.
Enantioselective Ni-Catalyzed Electrochemical Synthesis of Biaryl Atropisomers
Chen, Song,Chen, Yue-Gang,Gao, Pei-Sen,Liu, Dong,Ma, Hong-Xing,Mei, Tian-Sheng,Qiu, Hui,Shuai, Bin,Wang, Yun-Zhao
, p. 9872 - 9878 (2020/06/27)
A scalable enantioselective nickel-catalyzed electrochemical reductive homocoupling of aryl bromides has been developed, affording enantioenriched axially chiral biaryls in good yield under mild conditions using electricity as a reductant in an undivided cell. Common metal reductants such as Mn or Zn powder resulted in significantly lower yields in the absence of electric current under otherwise identical conditions, underscoring the enhanced reactivity provided by the combination of transition metal catalysis and electrochemistry.