Oxygen → HCID 21971269, compound

Participants

Reaction Conditions

Reaction Steps

Under a nitrogen atmosphere, diisopropylamine (3.93 ml, 28.0 mmol) was dissolved in anhydrous tetrahydrofuran (200 ml) to which, after cooling to −78° C., was subsequently added dropwise an n-hexane solution of 1.69 M n-butyl lithium (15.9 ml, 26.9 mmol) over a period of 10 minutes. After 20 minutes of stirring at 0° C. and subsequent cooling to −78° C., to the resulting reaction solution was added dropwise anhydrous tetrahydrofuran solution (40 ml) of 4-(S)-(1-ethoxycarbonylcyclopropyl)-1-[1-(S)-phenylethyl]-2-pyrrolidone (6.74 9, 22.4 mmol) over a period of 15 minutes. The reaction solution was stirred at −78° C. for 10 minutes and then the reaction vessel was charged with dried oxygen at the same temperature. The reaction solution was stirred at −78° C. for 20 minutes and then mixed with a saturated ammonium chloride aqueous solution (200 ml). This was warmed up to room temperature and the organic layer was separated. The aqueous layer was extracted with diethyl ether (200 ml×2), and the organic layers were combined and dried over anhydrous magnesium sulfate. After filtration, the filtrate was concentrated under reduced pressure, and the resulting residue was subjected to flash silica gel chromatography and eluted with an eluant of n-hexane:ethyl acetate=2:1, to thereby obtain 5.21 g (73%) of the title compound as a colorless oil.

Provenance & Evidence