Hydrochloric Acid → 2-Hydroxymethyl-chroman-4-one

The 3 g of 4-oxo-chromane-2-carboxylic acid in THF (65 mL) was stirred was cooled to 0° C. and borane-methyl sulfide complex (2.5 mL of M solution, 25 mmoles) was added dropwise for about 15 minutes. The solution was warmed to room temperature and then heated at reflux for 4 hours. The solution was cooled to room temperature and 10% aqueous hydrochloric acid (20 mL) was added over 15 minutes and the solution was stirred at room temperature for 2 hours. The mixture was concentrated to approximately 25 mL. The solution was poured into ethyl acetate (50 mL) and washed with water (2×30 mL), saturated sodium bicarbonate (2×30 mL) and saturated ammonium chloride (2×30 mL). The organic layer was separated dried over anhydrous MgSO4, and then concentrated in vacuo to yield about 2.6 g of 2-(hydroxymethyl)-chroman-4-one (86.7% yield)