S2 超音波を活用する有機合成反応例(特別講演2)

概要

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Various phenolic compounds were synthesized using ultrasonication in order to shorten the reaction time and get the good yields in mild condition. Our ultrasonication reactions were applied to the hydroxylation of phenols, oxidation reaction with Mn(III), C(II) and lipase. Various ketones were reacted with TiCl_4 and Zn under ultrasonication to give the corresponding coupling dimmers. Ketones were substituted with methoxy, hydroxy, acetoxy and bromine on the benzene ring. Using ultrasonication, the reaction time and yield of the reductive coupling reaction were changed better. Typical reaction was as follows. Substituted acetophenones were dissolved in THF. The solution was added with TiCl_4 and Zn in THF at 0℃ and the reaction mixture was ultrasonicated under argon. The reaction mixture was added by sodium hydrogencarbonate and the solution was extracted and the products were isolated. Various pinacols were produced concomitantly with pinacolones which were obtained with acid catalysis, TiCl_4. All structural determination of these products was done using NMR, IR, MS and X-ray analysis. The reaction with or without ultrasonication was extremely different in the reaction time. 4'-Hydroxy or 4'-methoxyacetophenone were reacted very easily with ultrasonication to give the corresponding substituted pinacols. Pinacols substituted with phenols were easily synthesized using ultrasonication.
日本ソノケミストリー学会の論文
2007-12-06