- Taming the carboxyl group for directed carbometalation: Observations on the use of anions, dianions and ester enolates
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Carboxylate anions, dianions and ester enolates provide simultaneous protection and activation for directed carbometalation reactions. Advantage can be taken of the bis-carbanionic character of the intermediate for further controlled C-C bond forming reac
- Desrat, Sandy,Gray, Philip J.,Penny, Matthew R.,Motherwell, William B.
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supporting information
p. 8918 - 8922
(2014/07/22)
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- Regioselective ring opening and isomerization reactions of 3,4-epoxyesters catalyzed by boron trifluoride
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Efficient ring opening of 3,4-epoxyesters with alcohols to produce 4-alkoxy-3-hydroxyesters and their isomerization into 4-ketoesters using boron trifluoride as the catalyst are presented. Both transformations are simple and efficient methods for the synthesis of the above named synthetically useful compounds.
- Izquierdo, Javier,Rodriguez, Santiago,Gonzalez, Florenci V.
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supporting information; experimental part
p. 3856 - 3859
(2011/09/19)
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- A practical, efficient, and atom economic alternative to the Wittig and Horner-Wadsworth-Emmons reactions for the synthesis of (E)-α,β- unsaturated esters from aldehydes
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We describe a highly efficient new methodology for the synthesis of (E)-α,β-unsaturated esters from aldehydes. In our DMAP-catalyzed reaction, both aromatic as well as aliphatic aldehydes furnish the desired products highly regio- and stereoselectively if treated with commercially available or synthetically easily accessible malonic acid half ester. A large scale application in the synthesis of p-methoxycinnamates, which are of use as sunscreen ingredients, is described.
- List, Benjamin,Doehring, Arno,Hechavarria Fonseca, Maria T.,Job, Andreas,Rios Torres, Ramon
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p. 476 - 482
(2007/10/03)
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- Palladium-Catalyzed Carbonylation of Allylamines. Synthesis of β,γ-Unsaturated Amides by One-Carbon Homologation of Allylamines
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Palladium-catalyzed carbonylation of allylamines under CO (50 atm) at 110 deg C proceeds highly efficiently to give the correponding β,γ-unsaturated amides.The carbonylation occurs at the less substituted carbon of allyl units to give linear amides with h
- Murahashi, Shun-Ichi,Imada, Yasushi,Nishimura, Koichi
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p. 453 - 464
(2007/10/02)
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- Palladium(0)-Catalyzed Alkoxycarbonylation of Allyl Phosphates and Acetates
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Palladium-catalyzed alkoxycarbonylation of allyl phosphates under CO (1 atm) at 50 deg C proceeds highly efficiently to give the corresponding β,γ-unsaturated esters.The carbonylation of geranyl phosphate ((E)-11) under CO (1 atm) at 50 deg C gave ethyl ester of homogeranic acid ((E)-12) stereoselectively.The carbonylation takes place at least substituted allylic positions with inversion of configuration.Typically, the methoxycarbonylation of cis-5-(methoxycarbonyl)-2-cyclohexen-1-yl phosphate (cis-16) gave trans-dimethyl-2-cyclohexene-1,5-dicarboxylate (trans-17) selectively.Alkoxycarbonylation of allyl acetates is performed for the first time in the presence of a catalytic amount of bromide ion.The reaction can be rationalized by assuming the mechanism which involves oxidative addition of palladium(0) species to allyl acetates to give ?-allylpalladium acetate, fast ligand exchange of the acetate with bromide, insertion of carbon monoxide to give acylpalladium species, and alkoxylation.
- Murahashi, Shun-Ichi,Imada, Yasushi,Taniguchi, Yuki,Higashiura, Shinya
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p. 1538 - 1545
(2007/10/02)
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- Stereochemistry of Deconjugative Alkylation of Ester Dienolates. Stereospecific Total Synthesis of the Litsenolides
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Deconjugative protonations, alkylations, and aldol condensations of the dienolates from (Z)-2-alkenoates give the corresponding (E)-3-enoate products, whereas dienolates from (E)-2-enoates give mainly the (Z)-3-enoate products.These generalizations are exploited in stereospecific total syntheses of litsenolides A2, B2, and C2.
- Kende, Andrew S.,Toder, Bruce H.
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p. 163 - 167
(2007/10/02)
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