- Enantioselective hydrolysis of N-acylated α-amino esters at a biphasic interface: Tandem reaction kinetic resolution using a chiral complexing agent
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equation presented Highly enantioselective hydrolytic kinetic resolutions of esters derived from N-acylated α-amino acids proceed rapidly at hydrocarbon/water interfaces in the presence of a proline-derived chiral selector. When performed in tandem with an enantioselective biphasic esterification reaction, esters of 100% enantiomeric excess are obtained.
- Snyder, Seth E.,Pirkle, William H.
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- 3,5-DINITROBENZOYL AMINO ACID ESTERS. BROADLY APPLICABLE CHIRAL SOLVATING AGENTS FOR NMR DETERMINATION OF ENANTIOMERIC PURITY.
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Methyl esters of N-(3,5-dinitrobenzoyl)-amino acids have been used as chiral solvating agents to induce NMR spectral nonequivalence between the enantiomers of a broad array of solutes.
- Pirkle, William H.,Tsipouras, Athanasios
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- Synthesis of (R)-(-) and (S)-(+)-3-(1-pyrrolyl)propyl- N-(3,5- dinitrobenzoyl)-α-phenylglycinate and derivatives. A suitable chiral polymeric phase precursor
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A synthetic route to obtain (R)-(-) (1), (S)-(+)-3-(1-pyrrolyl)propyl-N- (3,5-dinitrobenzoyl)-α-phenylglycinate (2) and derivatives is described. In a first step, pyrrole derivatives were prepared using the Clauson-Kaas method. The esterification, second step, was performed using basic conditions due to sensitivity of the pyrrole group toward acidic conditions. A tautomeric equilibrium involving the stereogenic center induces the product epimerization. The substitution of DMAP and Et3N by a highly hindered base, proton-sponge, furnished the final products without racemization. The ee of 1, 2 and of the corresponding methyl esters (3 and 4) were determined by 1H NMR analysis in the presence of optically active Eu(tfc)3. Epimerization was not observed in the preparation of the carboxylate salts (5-8).
- Ribeiro, Adriana Santos,Kanazawa, Alice,Navarro, Daniela M. A. F.,Moutet, Jean-Claude,Navarro, Marcelo
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p. 3735 - 3745
(2007/10/03)
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