Carbon tetrabromide → tert-Butyl 2-(2,2-dibromoethenyl)pyrrolidine-1-carboxylate

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Reaction Steps

To a stirred solution of triphenylphosphine (31.7 g, 120.8 mmol) and carbon tetrabromide (20.0 g, 60.3 mmol) in methylene chloride (450 mL) at 0° C. was added dropwise a solution of N-(tert-Butoxycarbonyl)-D-prolinal (6.0 g, 30.1 mmol) in methylene chloride (50 mL). Upon complete addition of the aldehyde, the cooling bath was removed and mixing continued for an additional 30 minutes at ambient temperature. The mixture was poured into saturated sodium bicarbonate solution (600 mL) and the organic layer was extracted, dried over sodium sulfate anhydrous, concentrated in vacuo and purified on a silica gel column using a 100% to 99:1 gradient of methylene chloride to methanol as mobile phase to yield pure tert-butyl 2-(2,2-dibromovinyl)pyrrolidine-1-carboxylate. LC-MS m/z (minus t-butyl+1)=300. 1H NMR (CDCl3, 400 Mhz) 6.37 ppm (s, 1H), 4.36 (s, 1H), 3.5-3.4 (m, 2H), 2.2-2.1 (m, 1H), 1.88-1.82 (m, 2H), 1.77-1.71 (m, 1H), 1.56 (s, 1H), 1.47 (s, 9H).

Provenance & Evidence