Dimethyl Sulfoxide → 5-Tert-butylpyridine-3-carbaldehyde

Oxalyl chloride (158 μL, 1.819 mmol) in methylene chloride (10 mL) was placed in a two-necked flask at −78° C., followed by the addition of dimethyl sulfoxide (129 μL, 1.819 mmol). Stirring was continued for 20 min, followed by addition of (5-tert-butylpyridin-3-yl)methanol (0.2 g, 1.21 mmol) in methylene chloride (10 mL). After the mixture was stirred at −78° C. for additional 20 min, triethylamine (0.59 mL, 4.24 mmol) was added. The cooling bath was removed and the suspension was allowed to warm to room temperature. Water (50 mL) was added, the yellow organic layer was separated, and the aqueous layer was extracted with methylene chloride (3×30 mL). The combined organic solution was dried and concentrated to give 5-tert-butylnicotinaldehyde as an orange-yellow liquid which was used directly for next step without further purification.