“…The crude residue was purified by silica gel column chromatography eluent: EtOAc/Cyclohexane 1:9) to afford compound 4o (124 mg, 0.34 mmol, 60%) as a white solid. 1 49 Compound 4s. According to the representative procedure, starting from p-toluenesulfonamide (1 equiv, 500 mg, 2.92 mmol) and benzoyl chloride (1.1 equiv, 0.37 mL, 3.21 mmol); flash chromatography on silica gel (EtOAc/Cy, 3:7) gave compound 4s (0.75 g, 2.72 mmol, 93%) as a white solid.…”