2,2-Difluoro-2-(fluorosulfonyl)acetic acid → (2S,4S)-1-tert-butyl 2-methyl 4-((difluoromethoxy)methyl)pyrrolidine-1,2-dicarboxylate

Participants

Reaction Conditions

Reaction Steps

A 100 mL round-bottom flask was charged with (2S,4S)-1-tert-butyl 2-methyl 4-(hydroxymethyl)pyrrolidine-1,2-dicarboxylate (3.33 g, 12.84 mmol), CuI (0.489 g, 2.56 mmol), and anhydrous acetonitrile (57.1 mL). The reaction was heated to 45° C. (ext. oil bath). 2,2-difluoro-2-(fluorosulfonyl)acetic acid (2.655 mL, 25.68 mmol) was added at 45° C. over 30 minutes via syringe pump. The reaction was heated for 30 minutes. Upon completion as monitored by TLC, the reaction mixture was cooled to room temperature and concentrated in vacuo. The crude residue was diluted in EtOAc and washed with sodium bicarbonate (aq). The bicarbonate layer was back extracted with ethyl acetate twice. Combined organic layers were washed with brine, dried over sodium sulphate, filtered and concentrated. The resulting residue was further purified via silica gel chromatography (10 to 40% EtOAc/Hexanes) to afford (2S,4S)-1-tert-butyl 2-methyl 4-((difluoromethoxy)methyl)pyrrolidine-1,2-dicarboxylate (2.41 g, 61%). MS (ESI) m/z 210.21 [M+H-Boc]+.

Provenance & Evidence