Synthesis of N-Fluorinated Sulfonamides

General procedure for the synthesis of N-F.
These substrates can be synthesized from Mitsunobu Reaction with 2-Aryl-2,3-butadien-1-ol and TsNHBoc, then the Boc protecting group can be removed by TFA.1.2-Phenyl-2, 3-butadien-1-ol (1.46g, 10 mmol), TsNHBoc (3.53g, 13 mmol) and PPh3 (3.41g 13 mmol) were suspended in THF (15 ml). The mixture was cooled to 0°C and diethyl azodicarboxylate (DEAD 2.61g, 15 mmol) was added dropwisely. Then the reaction mixture was allowed to warm to room temperature. Water was added when the starting material was disappeared and the mixture was extracted with Et₂O. The combined organic extracts were dried overMgSO₄. After solvent evaporated, the residue was purified through silica gel to give the allenyl imide product. The allenyl imide was treated with TFA following the process described as above to give the product (1.94g, 65% for two steps).In an oven dried round bottom flask with stir bar, sodium hydride (10 mmol, 2 equiv.) was taken. The sodium hydride was washed with pentane (2 times) and dried under vacuum and filled with nitrogen. Then dry DCM (40 mL) was added to it. A solution of sulfonamide (1 equiv.) in dry DCM (0.5 M) was added dropwise to the NaH suspension in DCM. The total reaction was stirred at room temperature for 30 mins. Then, a solution of NFSI (3 eq.) in dry DCM (0.5 M) was added to dropwise to the reaction mixture at room temperature. The total reaction mixture was stirred for overnight at room temperature. The reaction was quenched with ice with constant stirring. Then 50 mL of water was added to the reaction mixture. The organic part was washed with 30 mL NaHCO₃, and 30 mL brine solution respectively. The organic part was concentrated in rotary evaporator and performed silica gel flash column chromatography to isolate the desired N-F (fluorosulfonamide, 25%-50% yield) using hexanes/ethyl acetate mixture as eluent.