- Preparation of mono-substituted malonic acid half oxyesters (SMAHOs)
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The use of mono-substituted malonic acid half oxyesters (SMAHOs) has been hampered by the sporadic references describing their preparation. An evaluation of different approaches has been achieved, allowing to define the best strategies to introduce diversity on both the malonic position and the ester function. A classical alkylation step of a malonate by an alkyl halide followed by a monosaponification gave access to reagents bearing different substituents at the malonic position, including functionalized derivatives. On the other hand, the development of a monoesterification step of a substituted malonic acid derivative proved to be the best entry for diversity at the ester function, rather than the use of an intermediate Meldrum acid. Both these transformations are characterized by their simplicity and efficiency, allowing a straightforward access to SMAHOs from cheap starting materials.
- Condon, Sylvie,Le Gall, Erwan,Pichon, Christophe,Presset, Marc,Xavier, Tania
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supporting information
p. 2085 - 2094
(2021/09/02)
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- Asymmetric Synthesis of α-Trifluoromethylthio-β-Amino Acids under Phase Transfer Catalysis
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The first asymmetric α-trifluoromethylthiolation of 2-substituted isoxazolidin-5-ones was developed using Maruoka type N-spiro ammonium catalysts under phase-transfer conditions. The resulting products, containing a trifluoromethylthiolated quaternary chiral carbon, were obtained in moderate to good yields and up to 98:2 enantiomeric ratio. Moreover, the easy N-O bond cleavage provided access to undescribed α-trifluoromethylthio-β2,2-amino acids, with promising applications in biochemistry and medicinal chemistry.
- Capaccio, Vito,Sicignano, Marina,Rodríguez, Ricardo I.,Della Sala, Giorgio,Alemán, José
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p. 219 - 223
(2019/12/30)
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- Palladium-Catalyzed Asymmetric Allylic Alkylation of 4-Substituted Isoxazolidin-5-ones: Straightforward Access to β2,2-Amino Acids
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We report here an unprecedented and highly enantioselective palladium-catalyzed allylic alkylation applied to 4-substituted isoxazolidin-5-ones. Ultimately, the process provides a straightforward access to β2,2-amino acids bearing an all-carbon quaternary stereogenic center in great yields and a high degree of enantioselectivity.
- Nascimento de Oliveira, Marllon,Arseniyadis, Stellios,Cossy, Janine
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supporting information
p. 4810 - 4814
(2018/03/21)
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- Nucleophilic Reactivities of 2-Substituted Malonates
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Kinetics of the reactions of 2-substituted malonate anions and 5-substituted Meldrum's acid anions with benzhydrylium ions and structurally related quinone methides have been monitored in dimethyl sulfoxide solution at 20 °C. The resulting second-order rate constants followed the correlation lg k(20 °C) = sN(E + N), which allowed the nucleophile-specific parameters N and sN to be calculated for these highly stabilized carbanions and to integrate them in our comprehensive nucleophilicity scale. Given that the reactions of the benzhydrylium ions with the anions derived from 5-aryl-substituted Meldrum's acids did not proceed to completion, the corresponding equilibrium constants could be determined. In combination with available data for pyridines and benzoate ions, these equilibrium constants provide a direct comparison of the strengths of C-, N-, and O-centered Lewis bases with respect to C-centered Lewis acids.
- Puente, ángel,He, Shanshan,Corral-Bautista, Francisco,Ofial, Armin R.,Mayr, Herbert
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supporting information
p. 1841 - 1848
(2016/05/09)
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- Decarboxylative allylations of ester enolate equivalents
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A variety of ester enolate equivalents are generated in situ and undergo α-allylation in high yields via palladium-catalyzed decarboxylative allylation. The transformations are complete within very short reaction times under ambient conditions. Synthesis of α-allylated acyl derivatives provides access to other carboxylic acid and alcohol derivatives via acyl group substitution or reduction. This journal is
- Ariyarathna, Yamuna,Tunge, Jon A.
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supporting information
p. 8386 - 8389
(2014/12/10)
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- Functionalization of Csp3-H and Csp 2-H bonds: Synthesis of spiroindenes by enolate-directed ruthenium-catalyzed oxidative annulation of alkynes with 2-aryl-1,3-dicarbonyl compounds
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Ru(de) awakening: The synthesis of carbocycles by the ruthenium-catalyzed oxidative annulation of alkynes with 2-aryl cyclic 1,3-dicarbonyl substrates is described. Proceeding by the functionalization of C sp 3-H and C sp 2-H bonds, and the formation of an all-carbon quaternary center, the reaction provides a diverse range of spiroindenes in good yields with high levels of regioselectivity. Copyright
- Reddy Chidipudi, Suresh,Khan, Imtiaz,Lam, Hon Wai
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supporting information
p. 12115 - 12119
(2013/01/16)
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- A one pot synthesis of 5-phenyl-1,3-dioxane-4,6-dione derivatives
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A general procedure for synthesis of 5-phenyl-1,3-dioxane-4,6-dione derivatives is described. The synthesis involves the cycloaddition of (α- chlorocarbonyl)phenylketene with carbonyl compounds to generate the corresponding substituted 2-oxetanone's which is readily transformed to the final products in one step. The 1,3-dioxane-4,6-dione is a rigid cyclic structure, and can undergo easy hydrolysis.
- Saidi,Shaterian,Sheibani
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p. 2345 - 2351
(2007/10/03)
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- Intermediates for preparing α-carboxy-α-(3-thienyl)penicillin and cephalosporin derivatives
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A new process is disclosed for the preparation of alpha-carboxy-alpha-phenyl(or 3-thienyl)penicillin and cephalosporin derivatives. The process comprises reacting a 1.3-dioxane-4.6-dione derivative with the desired penicillanic or cephalosporanic acid derivative.
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