- Selective ortho-Alkylation of Phenols with Sulphoxides via Sigmatropic Rearrangement: Synthesis of Coumarins
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ortho-Alkylphenols have been prepared from phenol and dialkyl sulphoxides via sigmatropic rearrangement, using thionyl chloride or phenyl chlorosulphinate as an activator of sulphoxides.In the same manner, ortho-phenylthiomethylphenol has been prepared in good yields.When ethyl phenyl sulphoxide, diallyl sulphoxide, and methyl methylsulphinylacetate were used as sulphoxides, none of the expected products were obtained.Salicylaldehyde has been prepared in moderate yield, when methyl methylthiomethyl sulphoxide was used as a sulphoxide. 3-(2-Hydroxyphenyl)propionic acid derivatives, which were obtained from substituted phenols and dimethyl 3,3'-sulphynyldipropionate, have been cyclized to give the corresponding coumarins in good yields.
- Sato, Kikumasa,Inoue, Seiichi,Ozawa, Kimio,Kobayashi, Tohru,Ota, Tomomi,Tazaki, Michiko
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p. 1753 - 1756
(2007/10/02)
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- Ortho-Selective Alkylation of Phenols with Symmetric Sulfides and Sulfuryl Chloride
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Sulfuryl chloride has been shown to be useful activator for sulfides in the selective preparation of ortho-alkylated phenols via sigmatropic rearrangement.By this process, ortho-alkylated phenols have been prepared with various symmetric sulfides in good yields.The rearrangement products having 3-chloropropyl or 3-methyl-3-butenyl moiety have been converted into 2H-1-benzopyran derivatives.
- Sato, Kikumasa,Inoue, Seiichi,Miyamoto, Osamu,Ikeda, Hiroshi,Ota, Tomomi
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p. 4184 - 4186
(2007/10/02)
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- Pyrolyse de dithiocarbonates aromatiques et du pentaerythrol
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The thermolysis of dithiocarbonates derived from hydroxyphenols, aromatic glycols or pentaerythrol leads to elimination reactions, rearrangement or heterocyclization reactions according to their structures.
- Kryczka, Boguslaw,Descotes, Gerard
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p. 475 - 482
(2007/10/02)
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- Selective ortho-Methylthiomethylation of Phenols with Dimethyl Sulphoxide and Thionyl Chloride
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Thionyl chloride and phenyl chlorosulphinate have been shown to be useful activators for dimethyl sulphoxide in the selective preparation of ortho-methylthiomethylphenol via a sigmatropic rearrangement.By this process, ortho-methylthiomethylated phenols having a variety of 2- or 4-substituents (Me, Cl, OMe, NO2, and CO2Me) have been prepared in good yields.In contrast, similar reactions of 3-substituted phenols were affected by the electronic characters of the substituents.With more electron-donating groups such as OH and OMe in the 3-position, none of the expected products were obtained, but in the case of other 3-substituted phenols, two possible rearrangement products were obtained in moderate yields.
- Sato, Kikumasa,Inoue, Seiichi,Ozawa, Kimio,Tazaki, Michiko
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p. 2715 - 2719
(2007/10/02)
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- Reaction of Phenols with t-Butyl Bromide-Dimethyl Sulphoxide. Methylthiomethylation versus Bromination
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t-Butyl bromide-activated dimethyl sulphoxide reacts with phenols to give either methylthiomethylation or bromination products.Several equilibria are shown to be simultaneously present in the system; however, by appropriate choice of several parameters (basicity, temperature, and reactant ratio) it is possible to drive the reaction selectively in one direction.A general discussion on the mechanism of these reactions is given.
- Dossena, Arnaldo,Marchelli, Rosangela,Casnati, Giuseppe
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p. 1141 - 1144
(2007/10/02)
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