The first asymmetric synthesis of (S)- and (R)-5-hydroxythalidomides, one of thalidomide’s major metabolites, was achieved using HMDS/ZnBr2-induced imidation as a key reaction. 5-Hydroxythalidomide was found to be configurationally more stable than thalidomide at physiological pH. Stereochemical biological effects of thalidomide and 5-hydroxythalidomide on anti-angiogenesis and antitumor activities