- Pd/C-catalyzed deoxygenation of phenol derivatives using mg metal and MeOH in the presence of NH4OAc
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A Pd/C-catalyzed deoxygenation method of phenolic hydroxyl groups via aryl triflates or mesylates using Mg metal in MeOH at room temperature was developed. The addition of NH4OAc dramatically affects the reactivity and reaction rate. This method is particularly attractive to provide an environmentally benign and widely applicable removal method of phenolic alcohols under quite mild reaction conditions.
- Sajiki, Hironao,Mori, Akinori,Mizusaki, Tomoteru,Ikawa, Takashi,Maegawa, Tomohiro,Hirota, Kosaku
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- Palladium on carbon-diethylamine-mediated hydrodeoxygenation of phenol derivatives under mild conditions
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We have found that phenolic hydroxyl groups were readily deoxygenated via aryl sulfonate under the Pd/C-catalyzed hydrogenation conditions in the presence of diethylamine and the method could also be applicable to the hydrodeoxygenation of morphine to afford 3-deoxy-7,8-dihydromorphine. Diethylamine is not only a scavenger of the corresponding methanesulfonic acid derivative, which is produced during the reaction progress, but also a strong promoter of the Pd/C-catalyzed reduction of aryl sulfonates. This catalyst system could provide a general method for the deoxygenation of various phenol derivatives because of its mild reaction conditions, ease of handling, and no need of particular apparatus.
- Mori, Akinori,Mizusaki, Tomoteru,Ikawa, Takashi,Maegawa, Tomohiro,Monguchi, Yasunari,Sajiki, Hironao
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p. 1270 - 1280
(2007/10/03)
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- Mechanistic study of a Pd/C-catalyzed reduction of aryl sulfonates using the Mg-MeOH-NH4OAc system
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A method for the deoxygenation of phenolic hydroxy groups via aryl triflates or mesylates has been established by using a combination of Pd/ C-Mg-MeOH. The addition of NH4OAc to the system markedly accelerated the reaction rate and expanded the scope of the reaction. Mechanistic studies suggested that a single-electron transfer process from the Pd0 center to the benzene ring is involved in the reduction of aryl sulfonates and that NH4OAc works as a solubilization re agent of the Mg salt and as an accelerator of the electron transfer, thus enhancing the reaction process. Our method was also applicable to the regioselective deuteration of benzene derivatives with CH3OD as the solvent and deuterium source: the original hydroxy group could be efficiently replaced with a deuterium atom.
- Mori, Akinori,Mizusaki, Tomoteru,Ikawa, Takashi,Maegawa, Tomohiro,Monguchi, Yasunari,Sajiki, Hironao
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p. 1432 - 1441
(2008/02/04)
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- Compounds and their use in medicine, process for their preparation and pharmaceutical compositions containing them
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The present invention relates to novel antidiabetic, hypolipidemic, antiobesity and hypocholesterolemic compounds of formula (I), their derivatives, their analogs, their tautomeric forms, their stereoisomers, their polymorphs, their pharmaceutically acceptable salts, their pharmaceutically acceptable solvates and pharmaceutically acceptable compositions containing them.
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