Ammonium Chloride → (S)-4-Benzyl-3-(2-(4-bromo-2-methylphenyl)acetyl)oxazolidin-2-one

Participants

Reaction Steps

To 16B (11 g, 48.0 mmol) in CH2Cl2 (200 ml) was added oxalyl chloride (7.36 ml, 84 mmol) and DMF (0.112 ml, 1.441 mmol). The reaction was stirred at rt for 2 h. The solvent was removed and chased with ethyl acetate (2×). The residue was dried under high vac for 1.5 h. To (S)-4-benzyloxazolidin-2-one (10.21 g, 57.6 mmol) in THF (200 ml) at −78° C. was added n-butyllithium (1.6 M in hexanes, 36.0 ml, 57.6 mmol). The reaction was stirred for 25 min at −78° C. Then the above acylchloride dissolved in THF (100 mL) was added. The reaction was stirred at −78° C. for 1 h and then at rt for 15 min. Sat ammonium chloride was added to quench the reaction and ethyl acetate to dilute the reaction. The organic layer was then washed with water, brine, dried over sodium sulfate and concentrated. The crude product was purified by flash chromatography (0-50% ethyl acetate/hexanes). The desired fractions were combined and concentrated to give 16C (14.1 g, 36.3 mmol, 76% yield) as a white solid. 1H NMR (400 MHz, chloroform-d) δ ppm 7.38 (d, J=1.77 Hz, 1H) 7.27-7.38 (m, 4H) 7.16-7.23 (m, 2H) 7.06 (d, J=8.08 Hz, 1H) 4.64-4.76 (m, 1H) 4.14-4.36 (m, 4H) 3.32 (dd, J=13.26, 3.16 Hz, 1H) 2.79 (dd, J=13.39, 9.60 Hz, 1H) 2.26-2.32 (m, 3H).

Provenance & Evidence