作者:Naoya Shimojuh、Yumi Imura、Katsuhiko Moriyama、Hideo Togo
DOI:10.1016/j.tet.2010.11.111
日期:2011.2
Ion-supported Ph3P, 4-(diphenylphosphino)benzyltrimethylammonium bromide A and N-methyl-N-[4(diphenylphosphino)benzyl]pyrrolidinium bromide B, were used for the Wittig reaction. Ion-supported phosphonium salts A1 and B1, which were prepared from the reactions of ion-supported Ph3P A and B with ethyl bromoacetate, respectively, reacted with aromatic and aliphatic aldehydes in the presence of K2CO3 to give the corresponding alpha,beta-unsaturated ethyl esters in good yields with high purity by simple filtration of the reaction mixture and subsequent removal of the solvent from the filtrate. Similarly, ion-supported phosphonium salts A2 and B2, which were prepared from the reactions of ion-supported Ph3P A and B with p-methylbenzyl bromide, respectively, reacted with aromatic and aliphatic aldehydes in the presence of NaH to provide the corresponding p-methylstyrene derivatives in good yields with high purity by simple filtration of the reaction mixture and the subsequent removal of the solvent from the filtrate. In both reactions, the co-product, ion-supported Ph3PO, could be obtained quantitatively by simple filtration, and was converted into the corresponding ion-supported Ph3P A and B again in high yields using dimethyl sulfate, followed by the reduction with LiAlH4. Recovered and regenerated ion-supported Ph3P A and B could be reused for the same Wittig reaction while maintaining good yields of ethyl (E)-3-(4'-chlorophenyl)-2-propenoate and 1 -(4'-chlorophenyl)-2-(4 ''-methylphenyl)ethene with high purity by simple filtration and removal of the solvent from the filtrate. (C) 2010 Elsevier Ltd. All rights reserved.