The Experts below are selected from a list of 70536 Experts worldwide ranked by ideXlab platform
Igor Larrosa - One of the best experts on this subject based on the ideXlab platform.
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Carboxylation of Phenols with CO2 at Atmospheric Pressure
Chemistry: A European Journal, 2016Co-Authors: Sara Preciado, Igor LarrosaAbstract:A convenient and efficient method for the ortho-carboxylation of Phenols under atmospheric CO2 pressure has been developed. This method provides an alternative to the previously reported Kolbe-Schmitt method, which requires very high pressures of CO2 . The addition of a trisubstituted phenol has proved essential for the successful carboxylation of Phenols with CO2 at standard atmospheric pressure, allowing the efficient preparation of a broad variety of salicylic acids.
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overriding ortho para selectivity via a traceless directing group relay strategy the meta selective arylation of Phenols
Journal of the American Chemical Society, 2014Co-Authors: Junfei Luo, Sara Preciado, Igor LarrosaAbstract:The direct functionalization of Phenols at the ortho and para position is generally facilitated by the electron-donating nature of the hydroxyl group. Accessing meta-functionalized Phenols from the parent Phenols, on the other hand, generally requires lengthy synthetic sequences. Here, we report the first methodology for the one-pot direct meta-selective arylation of Phenols. This methodology is based on a traceless directing group relay strategy. In this process carbon dioxide is used as a transient directing group which facilitates a palladium catalyzed arylation meta to the phenol hydroxyl group with iodoarenes. This transformation proceeds with complete meta-selectivity and is compatible with a variety of functional groups both in the phenol and in the iodoarene coupling partner.
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Overriding Ortho–Para Selectivity via a Traceless Directing Group Relay Strategy: The Meta-Selective Arylation of Phenols
2014Co-Authors: Junfei Luo, Sara Preciado, Igor LarrosaAbstract:The direct functionalization of Phenols at the ortho and para position is generally facilitated by the electron-donating nature of the hydroxyl group. Accessing meta-functionalized Phenols from the parent Phenols, on the other hand, generally requires lengthy synthetic sequences. Here, we report the first methodology for the one-pot direct meta-selective arylation of Phenols. This methodology is based on a traceless directing group relay strategy. In this process carbon dioxide is used as a transient directing group which facilitates a palladium catalyzed arylation meta to the phenol hydroxyl group with iodoarenes. This transformation proceeds with complete meta-selectivity and is compatible with a variety of functional groups both in the phenol and in the iodoarene coupling partner
Yasumasa Hamada - One of the best experts on this subject based on the ideXlab platform.
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formal meta specific intramolecular friedel crafts allylic alkylation of Phenols through a spirocyclization dienone phenol rearrangement cascade
ChemInform, 2014Co-Authors: Mariko Yoshida, Tomoyuki Nozaki, Tetsuhiro Nemoto, Yasumasa HamadaAbstract:The Lewis acid catalyzed reaction yields 3,4-disubstituted Phenols from dienones in a highly efficient rearrangement or from allylic substituted phenoles in a cascade reaction.
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formal meta specific intramolecular friedel crafts allylic alkylation of Phenols through a spirocyclization dienone phenol rearrangement cascade
Tetrahedron, 2013Co-Authors: Mariko Yoshida, Tomoyuki Nozaki, Tetsuhiro Nemoto, Yasumasa HamadaAbstract:Abstract Formal meta-specific intramolecular Friedel–Crafts allylic alkylation of Phenols was achieved based on spirocyclization–dienone–phenol rearrangement cascades. Systematic screening of acid catalysts revealed that Sc(OTf)3 was a highly effective catalyst for dienone–phenol rearrangement of spiro[4.5]cyclohexadienones. Using 5 mol % of Sc(OTf)3 as the promoter, various spirocyclic substrates were transformed into the corresponding phenol derivatives in good to excellent yield. Furthermore, the one-pot sequential spirocyclization–dienone–phenol rearrangement proceeded using a palladium and scandium multi-catalytic system or a triphenylmethyl cation single-catalyst system, providing the corresponding meta-allylated phenol derivatives in excellent yield.
Mariko Yoshida - One of the best experts on this subject based on the ideXlab platform.
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formal meta specific intramolecular friedel crafts allylic alkylation of Phenols through a spirocyclization dienone phenol rearrangement cascade
ChemInform, 2014Co-Authors: Mariko Yoshida, Tomoyuki Nozaki, Tetsuhiro Nemoto, Yasumasa HamadaAbstract:The Lewis acid catalyzed reaction yields 3,4-disubstituted Phenols from dienones in a highly efficient rearrangement or from allylic substituted phenoles in a cascade reaction.
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formal meta specific intramolecular friedel crafts allylic alkylation of Phenols through a spirocyclization dienone phenol rearrangement cascade
Tetrahedron, 2013Co-Authors: Mariko Yoshida, Tomoyuki Nozaki, Tetsuhiro Nemoto, Yasumasa HamadaAbstract:Abstract Formal meta-specific intramolecular Friedel–Crafts allylic alkylation of Phenols was achieved based on spirocyclization–dienone–phenol rearrangement cascades. Systematic screening of acid catalysts revealed that Sc(OTf)3 was a highly effective catalyst for dienone–phenol rearrangement of spiro[4.5]cyclohexadienones. Using 5 mol % of Sc(OTf)3 as the promoter, various spirocyclic substrates were transformed into the corresponding phenol derivatives in good to excellent yield. Furthermore, the one-pot sequential spirocyclization–dienone–phenol rearrangement proceeded using a palladium and scandium multi-catalytic system or a triphenylmethyl cation single-catalyst system, providing the corresponding meta-allylated phenol derivatives in excellent yield.
Sara Preciado - One of the best experts on this subject based on the ideXlab platform.
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Carboxylation of Phenols with CO2 at Atmospheric Pressure
Chemistry: A European Journal, 2016Co-Authors: Sara Preciado, Igor LarrosaAbstract:A convenient and efficient method for the ortho-carboxylation of Phenols under atmospheric CO2 pressure has been developed. This method provides an alternative to the previously reported Kolbe-Schmitt method, which requires very high pressures of CO2 . The addition of a trisubstituted phenol has proved essential for the successful carboxylation of Phenols with CO2 at standard atmospheric pressure, allowing the efficient preparation of a broad variety of salicylic acids.
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overriding ortho para selectivity via a traceless directing group relay strategy the meta selective arylation of Phenols
Journal of the American Chemical Society, 2014Co-Authors: Junfei Luo, Sara Preciado, Igor LarrosaAbstract:The direct functionalization of Phenols at the ortho and para position is generally facilitated by the electron-donating nature of the hydroxyl group. Accessing meta-functionalized Phenols from the parent Phenols, on the other hand, generally requires lengthy synthetic sequences. Here, we report the first methodology for the one-pot direct meta-selective arylation of Phenols. This methodology is based on a traceless directing group relay strategy. In this process carbon dioxide is used as a transient directing group which facilitates a palladium catalyzed arylation meta to the phenol hydroxyl group with iodoarenes. This transformation proceeds with complete meta-selectivity and is compatible with a variety of functional groups both in the phenol and in the iodoarene coupling partner.
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Overriding Ortho–Para Selectivity via a Traceless Directing Group Relay Strategy: The Meta-Selective Arylation of Phenols
2014Co-Authors: Junfei Luo, Sara Preciado, Igor LarrosaAbstract:The direct functionalization of Phenols at the ortho and para position is generally facilitated by the electron-donating nature of the hydroxyl group. Accessing meta-functionalized Phenols from the parent Phenols, on the other hand, generally requires lengthy synthetic sequences. Here, we report the first methodology for the one-pot direct meta-selective arylation of Phenols. This methodology is based on a traceless directing group relay strategy. In this process carbon dioxide is used as a transient directing group which facilitates a palladium catalyzed arylation meta to the phenol hydroxyl group with iodoarenes. This transformation proceeds with complete meta-selectivity and is compatible with a variety of functional groups both in the phenol and in the iodoarene coupling partner
S Venkatesan - One of the best experts on this subject based on the ideXlab platform.
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extraction of phenol and chloroPhenols using ionic liquid bmim bf4 dissolved in tributyl phosphate
Clean-soil Air Water, 2013Co-Authors: Brinda A Lakshmi, A Balasubramanian, S VenkatesanAbstract:In the present work, experiments have been carried out with a focus to reduce the volume requirement of solvent by mixing with imidazolium based ionic liquids (ILs) for the solvent extraction of phenol, p-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, and pentachlorophenol from aqueous solutions. The effect of aqueous phase pH (2–12), agitation speed (100–450 rpm), solute concentration in feed (2–50 mg/L), temperature (303–333 K), treat ratio (1–11), and 1-butyl-3-methyl imidazolium tetrafluoroborate [Bmim]+[BF4]− volume in tributyl phosphate (TBP; 0–0.7% v/v) on extraction of Phenols has been studied and optimized. Parameters like strip phase pH (3–13) and stripping agent concentration (0.001–0.009 N) have also been studied for stripping of Phenols from solvent phase. It has been found that 0.5% v/v of ionic liquid [Bmim]+[BF4]− in solvent TBP extracts more than 97.5% of phenol and chloroPhenols from aqueous solutions with a treat ratio (aqueous to solvent phase ratio) of 5. Transport mechanism for extraction and stripping of phenol and chloroPhenols using ionic liquid [Bmim]+[BF4]− has been discussed. The results show that by appropriate selection of extraction and stripping conditions, it is possible to remove nearly all Phenols with a treat ratio of 5.
