Sodium Hydroxide → (Z)-2-[[2-chloro-4-[[(3-hydroxybenzyl)amino]carbonyl]benzoyl]amino]-3-[2-(1-methylethyl)-4-methylthiazol-5-yl]propenoic acid

An aqueous 1N solution of sodium hydroxide (1 mL, 1 mmol) was added to a solution of (Z)-2-[[2-chloro-4-[[(3-hydroxybenzyl)amino]carbonyl]benzoyl]amino]-3-[2-(1-methylethyl)-4-methylthiazol-5-yl)]propenoic acid methyl ester (Example 233; 65 mg, 0.123 mmol) in methanol/tetrahydrofuran (1:1; 2 mL). The solution was stirred at room temperature for 18 h, then at 50° C. for 6 h and finally at room temperature for 16 h. The reaction mixture was evaporated to dryness and after the addition of water the solution was acidified with 1N hydrochloric acid solution. The gelatinous colorless solid that precipitated was recovered by filtration and washed thoroughly with water. It was re-suspended in water and lyophilized. The obtained tacky material was dissolved in methanol (0.25 mL) and treated to constant turbidity with water. The resulting off-white solid was filtered off, washed with water/methanol (9:1) and dried in vacuo (45° C., 66 h) to give (Z)-2-[[2-chloro-4-[[(3-hydroxybenzyl)amino]carbonyl]benzoyl]amino]-3-[2-(1-methylethyl)-4-methylthiazol-5-yl]propenoic acid (41 mg, 65% yield) as an off-white powder.