N-(tert-Butoxycarbonyl)-D-prolinal → tert-Butyl (2R)-2-ethenylpyrrolidine-1-carboxylate

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Reaction Conditions

Reaction Steps

n-Butyl lithium (1.6 M in hexanes)(27 mL, 43 mmol) was added to ice-cold hexamethyldisilazane (9.2 mL, 44 mmol) under a nitrogen atmosphere. The solution was stirred for 10 min and was then added to a suspension of methyl(triphenylphosphonium)bromide (15.5 g, 43 mmol) in 100 mL of THF at ambient temperature. After stirring for 1 h, the mixture was cooled to −78° C. and a solution of tert-butyl (2R)-2-formylpyrrolidine-1-carboxylate (7.9 g, 40 mmol) in 50 mL of THF was added. The cold bath was removed and the mixture stirred overnight at ambient temperature. The reaction mixture was then quenched with saturated NH4Cl, the phases were separated, and the organic phase was washed with saturated NH4Cl, brine, dried over Na2SO4, filtered, and concentrated to give an orange oil. The oil was purified on a Biotage 40M column eluting with heptane to give tert-butyl (2R)-2-vinylpyrrolidine-1-carboxylate (5.0 g).

Provenance & Evidence