Hydrochloric Acid → Danosteine

To a solution of methyl 3-((2-methoxy-2-oxoethyl)thio)propanoate (5.0 g, 26 mmol) in THF/MeOH/water (60 mL, 4:1:1) was added lithium hydroxide monohydrate (4.375 g, 101 mmol). The resulting mixture was stirred at room temperature overnight before it was concentrated under reduced pressure. The residue obtained was diluted with water (˜100 mL) and the resulting solution was acidified with 6N HCl. The mixture was partitioned between water and ethyl acetate. The organic extract was washed with more water, separated, dried over sodium sulfate, filtered and evaporated to afford 3-((carboxymethyl)thio)propanoic acid (3.64 g, 85%) as a white solid. 1H NMR (300 MHz, DMSO-d6) δ ppm 2.55-2.57 (t, 2H) 2.75-2.79 (t, 2H) 3.27 (s, 2H) 12.41 (s, 2H)