Sulfur Dioxide → HCID 19434050, compound

Participants

Reaction Steps

To a solution of the product from Step D (3.22 g, 7.49 mmol) in anhydrous THF (30 mL) under nitrogen at -70° C. was added n-butyllithium (2.5M in hexanes, 3.30 mL, 8.24 mmol) via syringe over 5 min. The mixture was stirred for 30 min at which point a stream of sulfur dioxide was passed over the surface of the reaction mixture for about 5 min. The mixture was warmed to ambient temperature, evaporated to dryness and the residue was mixed with water (100 mL), cooled on an ice bath at which point hydroxylamine-O-sulfonic acid (1.69 g, 14.9 mmol) and NaOAc (4.07 g, 29.9 mmol) were added; after stirring for 5 min, a saturated solution of sodium bicarbonate (20 mL) was added. The reaction mixture was allowed to warm to ambient temperature and stirred for 16 hr followed by mixing with a saturated solution of sodium bicarbonate (50 mL) and extraction with ethyl acetate (2×200 mL). The combined extracts were washed with 2N HCl (100 mL). The aqueous layer was separated, stirred for 30 min, adjusted to pH 7 by the addition of potassium carbonate, and extracted with ethyl acetate (2×100 mL). The combined extracts were dried (MgSO4), evaporated to dryness and purified by column chromatography (silica, ethyl acetate to 10% ethanol/ethyl acetate, gradient) to give an oil (2.25 g, 69%).

Provenance & Evidence