Imidazole → tert-Butyl 3-iodopyrrolidine-1-carboxylate

Imidazole (2.62 g, 38.5 mmol), triphenylphosphine (10.1 g, 38.5 mmol), and tert-butyl 3-hydroxypyrrolidine-1-carboxylate (6.0 g, 32 mmol) were combined in 20 mL of THF and cooled in an ice bath. A freshly prepared solution of iodine (9.76 g, 38.5 mmol) in 20 mL of THF was then added at the rate of maintaining the internal temperature below 12° C. After the addition was complete, the reaction was allowed to warm to RT and stirred for 16 h. The reaction mixture was partitioned between MeOtBu and 10% NaHSO3. The aqueous layer was back extracted with MeOtBu (2×) and the combined orgnia layers were washed with brine, dried (Na2SO4) and concentrated. The crude material was chromatographed through a Redi-Sep pre-packed silica gel column (120 g), eluting with a gradient of 0% to 20% EtOAc in hexane, to provide tert-butyl 3-iodopyrrolidine-1-carboxylate as a colorless oil. MS (ESI, pos. ion) m/z: 241.6 (M−56).