l-6-Hydroxynorleucine, a key chiral intermediate used for synthesis of a vasopeptidase inhibitor, was prepared in 89% yield and> 99% optical purity by reductive amination of 2- keto-6-hydroxyhexanoic acid using glutamate dehydrogenase from beef liver. In an alternate process, racemic 6-hydroxynorleucine produced by hydrolysis of 5-(4-hydroxybutyl) hydantoin was treated with d-amino acid oxidase to prepare a mixture containing 2-keto-6 ...