[Synthetic organic reactions with mesoporous silicas].
Some hexagonal mesoporous silicas were attempted to use as a promoter for fine organic synthesis. Ti-HMS, a Ti-loaded hexagonal mesoporous silica, which possesses Lewis acid sites due to Ti-atom, was found to accelerate deprotection of benzyl ethers under hydrogenolytic conditions with palladium catalyst. Such acid-sensitive functional groups as silyl ether and acetal moieties in the molecule were little affected by Ti-HMS. MCM-41, a hexagonal mesoporous silica, /MeOH heterogeneous system was found to remove selectively and easily triethylsilyl (TES) group of silyl ethers of several types in the presence of t-butyldimethylsilyl (TBS) groups. FSM-16, another hexagonal mesoporous silica, was found to catalyze oxidative photodecarboxylation of alpha-hydroxy carboxylic acid and phenyl acetic acid derivatives to afford the corresponding carbonyl compounds. Furthermore, FSM-16 proved to be reuseable by recalcination at 450 degrees C after the reaction. Efficiency of these reactions was investigated concerning the solvent effect and activities of the promoters including common zeolites and ion-exchange resins.
Itoh
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Gifu Pharmaceutical University, 5-6-1 Mitahora-higashi, Gifu 502-8585, Japan.
D002384:Catalysis; D002625:Chemistry, Organic; D055601:Organic Chemistry Phenomena; D010084:Oxidation-Reduction; D016062:Porosity; D012822:Silicon Dioxide / Q000138:chemical synthesis / Q000737:chemistry
D012822:Silicon Dioxide