- Wittig reaction with ion-supported Ph3P
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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 α,β-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.
- Shimojuh, Naoya,Imura, Yumi,Moriyama, Katsuhiko,Togo, Hideo
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experimental part
p. 951 - 957
(2011/03/18)
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- Novel preparation of ion-supported triphenylphosphines and their synthetic utility
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Novel ion-supported Ph3P compounds, 4-(diphenylphosphino)- benzyltrimethylammonium bromide (A) and N-methyl-N-[4-(diphenylphosphino) -benzyl]pyrrolidinium bromide (B), were prepared. Because of their stability in air, ion-supported Ph3P A and B could be used for the halogenation of alcohols, the esterification of carboxylic acid with the Mitsunobu reaction, the Mizoroki-Heck reaction, and the Sonogashira reaction. The advantages of using these ion-supported Ph3P A and B are the simple isolation of the products by ether extraction due to their poor solubility in ether, and the easy recovery of the co-product, ion-supported Ph3PO, by filtration in high yields (>90%), which could be regenerated and reused for the same reactions, in the halogenation of alcohols and the esterification of carboxylic acid with the Mitsunobu reaction. On the other hand, ionic liquid reaction media containing Pd(OAc)2 or PdCl2 and ion-supported Ph3P A or B as catalysts could be reused for the same Mizoroki-Heck reaction and the Sonogashira reaction maintaining high yields, using iodotoluene with methyl acrylate and phenylacetylene, respectively.
- Imura, Yumi,Shimojuh, Naoya,Kawano, Yuhta,Togo, Hideo
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scheme or table
p. 3421 - 3426
(2010/06/19)
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