(S)-2-(3-((2-Isopropylthiazol-4-yl)methyl)-3-methylureido)-3-methylbutanoic acid

154248-99-4

154212-61-0

The general procedure for the synthesis of (S)-2-(3-((2-isopropylthiazol-4-yl)methyl)-3-methylureido)-3-methylbutanoic acid from N-((N-methyl-N-((2-isopropylthiazol-4-yl)methyl)amino)formyl)-L-valine methyl ester was as follows: compound 28 was prepared by reference to the method used for the preparation of compound 6 in Scheme 4, except that compound 9 was substituted for compound 4 as the starting material. Compound 28 (0.757 g, 2.31 mmol) was dissolved in THF (9 mL), and a freshly prepared aqueous 1M LiOH solution (4.6 mL, 4.6 mmol) was slowly added at room temperature. After 1.5 h of reaction, 1M HCl aqueous solution (7 mL, 7 mmol) was added to neutralize the reaction solution. Subsequently, the reaction mixture was extracted several times with EtOAc (5 × 15 mL). All organic layers were combined and dried with anhydrous sodium sulfate.