2,3-Dibromopropene → 1-(2-Bromoallyl)-pyrrolidin-2-one

Participants

Reaction Conditions

Reaction Steps

To a suspension of 5.0 g (40.6 mmol) of pyrrolidinone potassium salt prepared from Example 1 in 40 mL of toluene, solution of 5.24 mL (2 equiv.) of 2,3-dibromopropene in 10 mL of toluene was added dropwise for 1 hour in water bath and the reaction mixture was reacted at 60˜70° C. for 2 hours. Upon completion of the reaction, the mixture was cooled to 0° C. and filtered to remove solid. It was then concentrated under reduced pressure and purified by separation with silica gel column chromatography (ethyl acetate/n-hexane (1:1)) to obtain 5.30 g (64% yield) of 1-(2-bromoallyl)-pyrrolidin-2-one. To degassed solution of 1.0 g (4.90 mmol) of 1-(2-bromoallyl)-pyrrolidin-2-one prepared in the above in 50 mL of ethanol/benzene (1:1), 5 mol% (172 mg) of ditriphenylphosphine palladium dichloride, degassed solution of 7.35 mL of 2N sodium carbonate and 3-pyridyl-tributyltin, dimethyl borate, trimethyl borate lithium salt, boronic acid propanediol ring ester (2 equiv.), etc. were added. The mixture was reacted for 15 minutes at room temperature, followed by heating at reflux for 18 hours. After concentrating under reduced pressure, it was extracted with ethyl acetate for three times and washed with brine for two times. The concentrated solution was purified by separation with silica gel column chromatography (ethyl acetate followed by methylene chloride/methanol (20:1)) to obtain 810 mg (82% yield) of 1-(2-pyridin-3-yl-allyl)-pyrrolidin-2-one. Ozones were added to solution of 100 mg (0.494 mmol) of 1-(2-pyridin-3-yl-allyl)-pyrrolidin-2-one at −78° C. to obtain 1-(2-oxo-2-pyridin-3-yl-ethyl)-pyrrolidin-2-one, which was the same as synthesized in Example 20.

Provenance & Evidence