Sulfur Dioxide → HCID 19434100, compound

Participants

Reaction Conditions

Reaction Steps

To a solution of thiophene-3-carboxaldehyde ethylene acetal (5.82 g, 37.3 mmol) in anhydrous THF (50 mL) at -70° C. was added 2.5M n-butyllithium (16.4 mL, 41 mmol) over 10 min. The solution was stirred at -50° C. for 10 min, cooled to -70° C. for 30 min and sulfur dioxide was passed over the reaction mixture for 5 min. The mixture was allowed to warm to ambient temperature, the volatiles were evaporated and methylene chloride (200 mL) was added. The suspension was cooled (ice bath) and N-chlorosuccinimide (6.47 g, 48.5 mmol) was added. This mixture was stirred at ambient temperature for 2 h, filtered and the filter pad was washed with ethyl acetate (200 mL). The combined filtrates were added to a solution of sarcosine ethyl ester hydrochloride (15.0 g, 97.6 mmol) in saturated aqueous sodium bicarbonate (100 mL) and the mixture stirred for 4 h at ambient temperature. After the organic layer was separated, the aqueous layer was extracted with ethyl acetate (2×100 mL), the combined extracts were dried (MgSO4) and evaporated to dryness. Purification by column chromatography (silica, 30 to 50% ethyl acetate/hexane) gave an oil (8.95 g, 72%).

Provenance & Evidence