Hydrochloric Acid → 2-Cyclopropyl-1,3-thiazole-4-carboxylic acid

Lithium hydroxide monohydrate (0.13 g) was added to a solution of ethyl 2-cyclopropylthiazole-4-carboxylate (example 57, step b) (0.15 g) in a mixture of THF (8 mL) and water (2 mL) and the resulting mixture was stirred overnight. The reaction was acidified with aqueous HCl (2M, 3 mL) and the solvent evaporated. The residue was partitioned between brine (20 mL) and ethyl acetate (30 mL). The layers were separated and the aqueous phase extracted with ethyl acetate (2×30 mL). The combined organic solutions were dried over sodium sulphate, filtered and evaporated to give the subtitled compound as an off white solid. Yield 0.12 g.