Part A: Synthesis of tert-butyl 3-(trifluoromethylsulfonyloxy)-2,5-dihydro-1H-pyrrole-1-carboxylate
1. 1-tert-butoxycarbonyl-3-pyrrolidinone (370 mg, 2.0 mmol) was dissolved in THF (15 ml) at -78 °C.
2. lithium bis(trimethylmethylsilyl)amide (1M solution in THF, 2.2 ml, 2.2 mmol) was added slowly and the reaction mixture was stirred for 1 h at this temperature.
3. A solution of 2-[N,n-bis(trifluoromethanesulfonyl)amino]-5-chloropyridine (864 mg, 2.2 mmol) in THF (20 ml) was added dropwise.
4. the reaction mixture was continued to be stirred for 0.5 h, followed by a slow warming up to room temperature over a period of 3 h. The reaction was carried out by stirring.
5. The reaction was quenched with saturated sodium bicarbonate solution.
6. The reaction mixture was diluted with ethyl acetate and washed sequentially with 15% potassium bisulfate solution, saturated sodium bicarbonate solution, 1N sodium hydroxide solution, water and brine.
7. The organic layers were combined, dried with magnesium sulfate and concentrated in vacuum.
8. purification by fast chromatography (silica gel, 10% ethyl acetate/hexane) afforded tert-butyl 3-(trifluoromethylsulfonyloxy)-2H-pyrrole-1(5H)-carboxylate as a colorless oil (214 mg, 34% yield).
![2-[N,N-BIS(TRIFLUOROMETHANESULFONYL)AMINO]-5-CHLOROPYRIDINE](/CAS/GIF/145100-51-2.gif)
