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

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Reaction Conditions

Reaction Steps

To a solution of 3-(2,5,5-Trimethyl-1,3-dioxane-2-yl)thiophene (2.5 g, 11.7 mmol) in hexane (30 mL) cooled to 0° C. was added via syringe n-butyllithium in hexane (2.5 M, 10.3 mL, 25.7 mmol) over 5 min. The mixture was stirred at 0° C. for 20 min, the ice bath was removed and the stirring was continued for 30 min. At this time a white precipitate formed. The mixture was cooled to -60° C. and THF (20 mL) was added. Sulfur dioxide was then passed through the surface of the mixture for 30 min. The mixture was warmed to ambient temperature and stirred for an additional 15 min. The volatiles were evaporated and to the residue was added water (50 mL) and sodium acetate trihydrate (9.55 g, 70.2 mmol). The solution was cooled on an ice bath and hydroxylamine-O-sulfonic acid (4.62 g, 40.9 mmol) was added. The mixture was stirred at ambient temperature for 1 h, extracted with ethyl acetate (3×100 mL) and the combined extracts were washed with a sodium bicarbonate solution, brine and dried over molecular sieves. Evaporation to dryness gave a viscous liquid (4.93 g), which was chromatographed (silica, eluting with 33% ethyl acetate-hexane) to give a solid (2.47 g, 72%): mp 200°-202° C.

Provenance & Evidence