Dimethyl Sulfoxide → 5-Acetylamino-2-formyl-2,4,6,7-tetramethyl-2,3-dihydrobenzofuran

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Reaction Steps

A solution of oxalyl chloride (0.45 ml, 4.7 mmol) in dichloromethane (10 ml) was cooled to -78° C. and dimethyl sulfoxide (1 ml) was added dropwise with stirring. After stirring at the same temperature for 2 hours, a solution of 5-acetylamino-2-hydroxymethyl-2,4,6,7-tetramethyl-2,3-dihydrobenzofuran (1.1 g, 4.2 mmol) in dichloromethane (5 ml) was added dropwise and the mixture was stirred for additional 30 minutes. Triethylamine (3.5 ml) was added and the mixture was stirred for 10 minutes. The reaction mixture was washed with 1N hydrochloric acid and aqueous saturated sodium bicarbonate solution. The reaction mixture was dried and then concentrated. The residue was purified by column chromatography on silica gel (ethyl acetate) to obtain the desired compound (0.47 g, yield: 43.1%) as oil.

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