Into a 0° C. solution of N-(3-methoxycarbonylphenyl) pyrid-3-ylmethylamine (204 g, 0.842 mole, 1 eq) in dichloroethane (3610 mL) and pyridine (1775 mL) was added ethanesulfonyl chloride (114 mL, 1.2 mole, 1.43 eq). The reaction was allowed to warm to room temperature overnight. The dark red reaction was stirred with potassium carbonate (204 g) for 30 minutes and then filtered and concentrated to dryness. The residue was purified by Biotage, eluting with 3:1 to 2:1 DCM/EtOAc mixture to give the title compound as a white solid (137.0 g, 49% yield).
