| 摘要 |
The invention is concerned with two new, optically active forms of 2-keto-3-methyl-4-hydroxy-valeric acid of the formula <IMG> I wherein the C atom 4 has the (S)-configuration. The C atom 3 can have the (R)-configuration or the (S)-configuration. The invention is also concerned with a microbiological process for the manufacture of the compounds I. This process comprises reacting 4-hydroxy-isoleucine (2S, 3R, 4S) (= L-4-hydroxyisoleucine) of the formula <IMG> II with microorganisms which have L-amino acid oxidase (EC 1.4.3.2.) activity or with a L-amino acid oxidase. The compounds I are interesting intermediates for the production of the optically active (5S)-3-hydroxy-4,5-dimethyl-2(5H)-furanone.
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