Sodium Hydroxide → 3-[(2-Tetrahydropyranyl)oxy]propanoic acid

Sodium hydroxide (2M, 349 mL, 697.58 mmol) was added to a solution of methyl 3-(tetrahydro-2H-pyran-2-yloxy)propanoate (67.68 g, 359.58 mmol) in THF (680 mL) at room temperature. The reaction mixture was stirred at room temperature for 3 hours. The THF was removed in vacuo, the aqueous layer was then washed with ethyl acetate (260 mL), before cooling to 0° C. and careful acidification to pH 5 by the addition of hydrochloric acid (2M). The product was extracted with ethyl acetate (3×250 mL) before drying (MgSO4) and evaporation to give 3-(tetrahydro-2H-pyran-2-yloxy)propanoic acid (57.0 g, 91%) as a clear oil. This material was dissolved in ethyl acetate (750 mL) then washed with water (3×250 mL) and brine (250 mL) to remove remaining acetic acid. The organic solution was dried (MgSO4) and evaporated to give 3-(tetrahydro-2H-pyran-2-yloxy)propanoic acid (45.67 g 72.9%) as a colourless oil: 1H NMR Spectrum: 1H NMR (CDCl3) 1.43-1.67 (4H, m), 1.65-1.95 (2H, m), 2.68 (2H, t), 3.48-3.58 (1H, m), 3.73 (1H, dt), 3.88 (1H, ddd), 4.02 (1H, dt), 4.59-4.7 (1H, m); Mass Spectrum [M−H]−=173.