(2S)-2-acetamido-3,3-dimethylbutanoic acid

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: The above commercially available L-aminoacylase (Comparative Example 2) (0.5 mL) was added to the reaction reagent (9.5 mL) containing the above N-acetyl-L-tert-leucine and, after the above was gently stirred, the reaction was conducted at 25° C. for 12 hours. As a control test, the same reaction was conducted by adding 50 mM K-phosphate buffer (pH 7.5) to the reagent mixture in place of the L-aminoacylase solution. After the enzymatic reaction, the L-amino acid was directly detected by TLC and ninhydrin reaction by the same manner as in Example 2. As a control test, the same reaction After the enzymatic reaction

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: L-tert-Leucine (manufactured by Tokyo Kasei Kogyo) (4.7 g) was suspended in glacial acetic acid (manufactured by Nakarai Tesk, 40 mL) and heated at 40 to 50° C. together with addition of thrice molar acetic acid anhydride (manufactured by Nakarai Tesk) thereto whereupon the reaction was conducted. After glacial acetic acid was removed in vacuo, the crude crystals were obtained. After that, the crude crystals were recrystallized from 20% isopropyl alcohol. The precipitate was ground in a mortar and dried to give powder of N-acetyl-L-tert-leucine. Details thereof are mentioned in J. P. Greenstein, Chemistry of Amino Acids, 1961, 3. After glacial acetic acid was removed in vacuo the crude crystals were obtained After that, the crude crystals were recrystallized from 20% isopropyl alcohol dried