N1CC(=O)NC1=O.[NH2:8][C@@H:9]([C:14]([OH:16])=[O:15])[C@H:10]([CH2:12][CH3:13])[CH3:11].N1CC(=O)NC1=O.N[C@H](C(O)=O)[C@H](CC)C.N1CC(=O)NC1=O.C(N[C@H](C(O)=O)[C@H](CC)C)(=O)N>C[C@@H](CC)C=O>[NH2:8][C@H:9]([C:14]([OH:16])=[O:15])[C@H:10]([CH2:12][CH3:13])[CH3:11]In another embodiment, as shown in Scheme 4, the invention is directed to a method for producing L-isoleucine comprising converting (S)-2-methylbutyraldehyde to a diastereomeric mixture of D-allo-isoleucine hydantoin and L-isoleucine hydantoin under conditions whereby no significant racemization of the chiral center in (S)-2-methylbutyraldehyde occurs, followed by contacting said diastereomeric hydantoin mixture with an L-hydantoinase to stereoselectively hydrolyze any L-isoleucine hydantoin in the mixture to the corresponding N-carbamoyl-L-isoleucine. Preferably in the claimed method the contacting of the diastereomeric hydantoin mixture with an L-hydantoinase is carried out under conditions permitting the simultaneous epimerization of the chiral center at C-5 of the hydantoin. As discussed further below, the simultaneous epimerization permits the reaction to be carried out to substantial completion so that the diastereomeric hydantoin mixture is converted to N-carbamoyl-L-isoleucine in high yield. The N-carbamoyl-L-isoleucine is then decarbamoylated to produce L-isoleucine.
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