Sodium Carbonate → Tert-butyl (2r)-2-(2,2-dibromovinyl)pyrrolidine-1-carboxylate

Participants

Reaction Conditions

Reaction Steps

Carbon tetrabromide (49.2 g, 0.15 mol) in methylene chloride (150 mL) was added at 0° C. to a stirred solution of triphenyl phosphine (78.2 g, 0.30 mol) in methylene chloride (600 mL) under nitrogen. The solution was stirred at 0° C. for 1 hr. and (R)-t-butyl 2-formyl-1-pyrrolidinecarboxylate (21.9 g, 0.10 mol) was added. After 30 min. a solution of sodium carbonate (75 g, 0.75 mol) in water (300 mL) was added. The phases were separated and the aqueous phase was reextracted with methylene chloride (200 mL). The organic phase was washed with water (40 mL), and the majority of solvent was removed under reduced pressure leaving the material in a minimum of methylene chloride. Ethyl acetate (500 mL) was added and the resulting precipitate of triphenylphosphine oxide was filtered off. The mother liquors were evaporated and filtered repeatedly to remove additional triphenylphosphine oxide. The residual solid in ethyl acetate was then concentrated and applied to a silica gel column. Elution with ethyl acetate:Skellysolve B (1:10) gave 31.6 g (91%) of product. This was crystallized from petroleum ether to give 25.8 g of product, m.p. 64°-67° C. The analytical sample was recrystallized from ethyl acetate:Skellysolve B. [α]D -21° (c 0.81, MeOH).

Provenance & Evidence