P8 還元的カップリング反応への超音波照射の影響(ポスターセッション)

概要

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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(2.84mmol) were dissolved in THF. The solution was added with TiCl_4(4.60mmol) and Zn(9.07mmol) in THF at 0℃ and the reaction mixture was ultrasonicated under argon. The reaction mixture was added by sodium hydrogencarbonate and solution and extracted with ethyl acetate. The ethyl acetate extracts were concentrated in vacuo and the concentrated solution was chromatographed over silica gel, eluted with hexane-ethyl acetate, to give the corresponding dimer in good yield. In this reaction, various pinacols were produced concomitantly with pinacolones which were rearranged 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
2006-10-27