A separate 100 mL oven-dried round-bottom flask was fitted with a nitrogen balloon and charged with a stir bar, 7 (3.6 g, 11.75 mmol, 1 equiv.), and DMA (25 mL). The reaction flask was cooled to 0 °C using an ice-water bath, and freshly prepared ClSO2NH2 (in 12 mL of CH3CN) was added dropwise. The reaction mixture was warmed to room temperature over a period of 2 hours. Following this time, the reaction was quenched by addition of saturated aqueous NaHCO3 solution (20 mL). The mixture was transferred to a separatory funnel and further diluted with water (20 mL). The aqueous layer was extracted with EtOAc (3 x 30 mL). The organic layers were combined, dried over MgSO4, and concentrated under reduced pressure.