METHOD OF PREPARING OPTICALLY ACTIVE ESTERS OF ERYTHRO-3-AMINO-2- HYDROXYBUTYRIC ACIDS AND CORRESPONDING ACIDS Russian patent published in 2001 - IPC

FIELD: organic synthesis. SUBSTANCE: invention provides method for preparing optically active esters of erythro-3-amino-2-hydroxybutyric acids, valuable intermediate for pharmaceutical reagents, in particular HIV protease inhibitor, having general formula III: (III), wherein R¹ is phenyl or cyclohexyl group, R² protective group, and R³ optionally substituted C1-C6-alkyl; and steric configuration *3 represents S or R configuration. Method consists in oxidation of hydroxyl group in position 2 of 3-amino-2-hydroxybutyric acid ester with optical active center in position 3 as indicated in formula I: (I), wherein R¹, R² and R³ are defined as above and steric configuration *3 represents S or R configuration, to form optically active 3-amino-2- oxobutyric acid ester represented by formula II: (II), wherein R¹, R², R³ and *3, independently from each other, are the same significances as above, after which carbonyl group in position 2 is subjected to erythro-selective reduction by the aid of aluminum alkoxide. EFFECT: increased yield and purity of product. 3 cl, 2 ex