Stereoselective ring opening of chiral oxazolidines by reformatsky reagents: An enantioselective entry to β-amino esters

Article abstract of DOI:10.1016/S0040-4039(00)78889-7

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%).