61477-39-2Relevant articles and documents
Catalytic Hydrogenation of Chiral α-Amino and α-Hydroxy Esters at Room Temperature with Nishimura Catalyst without Racemization
Studer, Martin,Burkhardt, Stefan,Blaser, Hans-Ulrich
, p. 802 - 808 (2007/10/03)
The hydrogenation of carboxylic acid derivatives at room temperature was investigated. With a mixed Rh/Pt oxide (Nishimura catalyst), low to medium activity was observed for various α-amino and α-hydroxy esters. At 100 bar hydrogen pressure and 10% catalysts loading, high yields of the desired amino alcohols and diols were obtained without racemization. The most suitable α-substituents were NH2, NHR, and OH, whereas β-NH2 were less effective. Usually, aromatic rings were also hydrogenated, but with the free bases of amino acids as substrates, some selectivity was observed. No reaction was found for α-NR2, α-OR, and unfunctionalized esters; acids and amides were also not reduced under these conditions. A working hypothesis for the mode of action of the catalyst is presented.
Stereoselective ring opening of chiral oxazolidines by reformatsky reagents: An enantioselective entry to β-amino esters
Andres, Celia,Gonzalez, Alfonso,Pedrosa, Rafael,Perez-Encabo, Alfonso
, p. 2895 - 2898 (2007/10/02)
Chiral oxazolidines obtained by condensation of aldehydes with (-).(R)- or (+).(S)-N-benzylphenylglycinol react with the Reformatsky reagent derived from ethyl bromoacetate, in mild reaction conditions (Et2O or CH2Cl2, 0°C, 15-60 min), leading to ethyl β-amino carboxylates in moderate to good diastereomeric excess (60-92%). These ring opening products are transformed into primary β-aminoesters, in one step, by debenzylation with H2/Pd on carbon without loss of their stereochemical integrity. In this way, ethyl β-amino carboxylates can be obtained in both enantiomeric forms, with chemical yields ranging 55-76% and moderate to good e.e. (60-92%).
