Sulfur Dioxide → 3-(2,5,5-Trimethyl-1,3-dioxan-2-yl)thiophene-2-sulfonamide

Participants

Reaction Steps

To a solution of 3-(2,5,5-trimethyl-1,3-dioxan-2-yl)thiophene (106 g, 0.5 mol) in hexane (1200 mL) at -60° C. was added a 2.5M solution of n-butyllithium in hexane (240 mL, 0.6 mmol) over 40 min. The mixture was allowed to warm to room temperature (approximately 1.5 hr) and then once again cooled to -60° C. and anhydrous THF (400 mL) added. Sulfur dioxide was passed over the surface of the reaction mixture for 30 min at which point the reaction mixture was allowed to warm to room temperature under a positive SO2 pressure (approximately 1 hr). The solvent was removed and the residue dissolved in water (1200 mL) to which sodium acetate trihydrate (217.73 g, 1.6 mol) was added. The solution was cooled (ice bath) to 0° C. and hydroxylamine-O-sulfonic acid (107 g, 0.95 mol) was slowly added. The mixture was stirred at room temperature for 18 hr and then extracted with ethyl acetate. The combined extracts were washed with a saturated aqueous sodium bicarbonate solution, brine, dried (Na2SO4) and evaporated to give a viscous brown oil (174.05 g); this product was used in the next step without further purification.

Provenance & Evidence