Organocatalytic asymmetric 5-hydroxyisoxazolidine synthesis: A highly enantioselective route to beta-amino acids

The highly chemo- and enantioselective organocatalytic tandem reaction between N-protected hydroxyl amines and a, beta-unsaturated aldehydes is presented; the reaction provides access to 5-hydroxyisoxazolidines and beta-amino acids in high yields and with 90-99% ee.