Stereoselective Synthesis of β-Substituted Aspartic Acids via Tetrahydro-1,3-oxazin-6-ones.-The chiral oxazinone (III) derived from the aspartate α-ester urethane (I) undergoes a diastereoselective alkylation. Simple acidic hydrolysis of the resulting products [cf. (Va)] yields enantiopure 3-alkylaspartic acids, e.g. (VIII). -(BURTIN, GUILLAUME; CORRINGER, PIERRE-JEAN; HITCHCOCK, PETER B.; YOUNG, DOUGLAS W.; Tetrahedron Lett. 40 (1999) 22, 4275-4278; Sussex Cent. Biomol. Design Drug Dev., Univ. Sussex, Brighton BN1 9QJ, UK; EN)