Under argon protection, (R)-tetrahydrofuran-2-carboxylic acid (2 g, 17.22 mmol) was dissolved in 20 mL of tetrahydrofuran (THF) and the reaction flask was cooled in an ice bath. Borane-dimethyl sulfide complex (BH3-SMe2, 2M THF solution, 10 mL, 20.0 mmol) was slowly added to the reaction solution over 10 min. After removing the ice bath, the reaction mixture was stirred at room temperature for 1 hour. Subsequently, the reaction mixture was again cooled in an ice bath and methanol was slowly added until no gas escaped. Finally, the reaction solution was concentrated under reduced pressure to afford the target product tetrahydrofurfuryl alcohol as an oil (1 g, 60% yield). The product was characterized by 1H NMR (300 MHz, CDCl3): δ 1.55-1.70 (m, 1H), 1.72-1.98 (m, 3H), 3.35-4.00 (m, 6H).
