Ethyl Acetate → Mannitol

Participants

Reaction Conditions

Reaction Steps

The monosilylated material (2) (90 g, 0.20 mol) was dissolved in 1 L of distilled methanol and the solution cooled to 0° C. under an inert atmosphere. Sodium borohydride (36 g, 0.98 mol) was added portionwise over 1.5 hour at 0–5° C. The mixture was allowed to warm to room temperature with stirring over 16 hours. The majority of the methanol (approx. 700 mL) was removed under reduced pressure and the resulting grey suspension was diluted with water (250 mL). Hydrochloric acid (1 M; 190 mL) was added dropwise at room temperature to provide a white suspension. Ethyl acetate (500 mL) was added and the suspension stirred for 30 minutes to provide homogeneous aqueous and organic phases. The aqueous layer was separated and further extracted with 2×500 mL of ethyl acetate. The organic layers were combined and washed with saturated, aqueous sodium bicarbonate (300 mL) and saturated, aqueous sodium chloride (300 mL), dried over magnesium sulfate and concentrated under reduced pressure to afford the crude product as a colourless foam (79 g). The foam was subjected to dry-flash chromatography to provide (3) (65 g, 72%) as a colourless foam. Rf 0.51 (methanol/ethyl acetate, 0.5:9.5). 1H NMR (300 MHz, DMSO-d6) δ: 7.76 (1H, d, J=7.9 Hz), 7.69–7.66 (4H, m), 7.45–7.39 (6H, m), 4.63–4.57 (2H, m), 4.39 (1H, d, J=5.2), 4.27 (1H, d, J=7.6), 3.85–3.58 (7H, m), 3.43–3.38 (1H, m), 1.85 (3H, s), 0.99 (9H, s). 13C NMR (300 MHz, DMSO-d6) δ: 171.2, 135.6, 135.5, 133.9, 133.8, 130.0, 128.1, 70.9, 69.5, 68.6, 66.7, 61.1, 53.4, 27.0, 22.9, 19.3.

Provenance & Evidence