Triethylamine → 1-(4(S)-benzyl-oxazolidin-2-on-3-yl)-2-[1-(4-fluorophenyl)-1H-pyrrol-3-yl]-ethanone

Participants

Reaction Steps

To a solution of (S)-(−)-4-benzyl-2-oxazolidinone (710 mg, 4 mmol) in dry THF (10 mL) at −78° C. was added n-butyllithium (2.5 mL of 1.6 M in hexanes). In a separate reaction vessel, to a solution of 2-[1-(4-fluorophenyl)-1H-pyrrol-3-yl]-acetic acid (920 mg, 4.2 mmol) and triethylamine (0.7 mL, 5 mmol) in dry THF (20 ml) at −78° C. was added dropwise pivaloyl chloride (0.5 mL, 4 mmol). After stirring at −78° to 0° C. over 1 hour, then recooling to −78° C., the above solution was added via cannula. The resultant mixture was allowed to warm to ambient temperature over 17 hours, then partitioned with EtOAc and aqueous NH4Cl. The separated aqueousueous phase was extracted with EtOAc. The combined organic layers were washed with brine, dried over Na2SO4, and concentrated to an oil, which was purified via flash column chromatography with 15-20% EtOAc/hex gradient eluant. The oily product crystallized from benzene to give 1.04 g (69%) of 1-(4(S)-benzyl-oxazolidin-2-on-3-yl)-2-[1-(4-fluorophenyl)-1H-pyrrol-3-yl]-ethanone as a solid, mp 106-8° C. 1H NMR: δ 7.36-7.25 (m, 5H), 7.17-7.07 (m, 4H), 7.04 (s, 1H), 6.98 (t, 1H, J=2.6 Hz), 6.35 (dd, 1H, J=1.8, 2.6 Hz), 4.72-4.67 (m, 1H), 4.28-4.14 (m, 4H), 3.28 (dd, 1H, J=3.3, 3.6 Hz), 2.79 (dd, 1H, J=9.4, 13.4 Hz). Anal. Calculated for C22H19N2O3F: C, 69.83; H, 5.06; N, 7.40. Found: C, 69.80; H, 5.07; N, 7.30.

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