155820-05-6Relevant articles and documents
Cobalt-Catalysed Reductive Etherification Using Phosphine Oxide Promoters under Hydroformylation Conditions
Beller, Matthias,Delolo, Fábio G.,Fessler, Johannes,Gusevskaya, Elena V.,Junge, Kathrin,Neumann, Helfried,dos Santos, Eduardo N.
supporting information, (2022/02/19)
A phosphine-oxide-promoted, cobalt-catalysed reductive etherification using syngas as a reductant is reported. This novel methodology was successfully used to prepare a broad range of unsymmetrical ethers from various aldehydes and alcohols containing diverse functional groups, and was scaled-up to multigram scale under comparably mild conditions. Mechanistic experiments support an acetalization–hydrogenation sequence.
Visible light mediated oxidation of benzylic sp3 C-H bonds using catalytic 1,4-hydroquinone, or its biorenewable glucoside, arbutin, as a pre-oxidant
Finney, Laura C.,Mitchell, Lorna J.,Moody, Christopher J.
supporting information, p. 2242 - 2249 (2018/05/28)
Benzylic ethers undergo a visible light induced C-H activation and oxygen insertion to give the corresponding benzoate esters in moderate to good yields. The conditions employ substoichiometric amounts of 1,4-hydroquinone with copper(ii) chloride dihydrate as an electron-transfer mediator, oxygen as the terminal oxidant and dimethyl carbonate as solvent under visible light irradiation. The naturally occurring glucoside, arbutin, which is commercially available or can be accessed via extraction of the leaves of bearberry (Arctostaphylos uva-ursi) or elephant ears (Bergenia crassifolia) can be used as a biorenewable source of 1,4-hydroquinone. The methodology exploits the increase in oxidizing ability of quinones upon irradiation with visible light, and offers a sustainable alternative for the late stage oxidative functionalization of benzylic C-H bonds. It is applicable to a range of cyclic benzylic ethers such as isochromans and phthalans, and simple benzyl alkyl ethers. It can also be applied in the oxidation of benzylic amines into amides, and of diarylmethanes into the corresponding ketones. Mechanistic studies suggest that the reaction proceeds by H-abstraction by the photo-excited triplet benzoquinone to give a benzylic radical that subsequently reacts with molecular oxygen.
Correlation of the rates of solvolysis of (arylmethyl)methylphenyl-sulfonium ions
Kevill, Dennis N.,Ismail, Norsaadah H.J.
, p. 1865 - 1868 (2007/10/03)
The specific rates of solvolysis of the benzylmethylphenylsulfonium ion (prepared as the trifluoromethanesulfonate salt) and five benzylic ring-substituted derivatives can be satisfactorily correlated using NT solvent nucleophilicity values. Addition of a secondary term, governed by the aromatic ring parameter (I), shows the sensitivities towards changes in this parameter to fall and those towards changes in NT to rise with increasing electron-withdrawing ability of the substituent. The Hammett ρ values with electron-withdrawing substituents (based on ρ+ values) vary from -0.9 in 95% acetone to -1.8 in 97% 2,2,2-trifluoroethanol. These Grunwald-Winstein and Hammett analyses are compared to those previously reported, with essentially the same solvents and substituents, for solvolyses of arylmethyl p-toluenesulfonates.
