(4R,5S)-(+)-4-Methyl-5-phenyl-2-oxazolidinone → (4R,5S)-4-methyl-3-(4,4,4-trifluorobutyryl)-5-phenyl-2-oxazolidinone

Participants

Reaction Steps

A solution of n-butyllithium (2.0 mole) in hexane was added to a stirred solution of (4R,5S)-(+)-4-methyl-5-phenyl-2-oxazolidinone (353 g) in dry tetrahydrofuran (2500 ml) at -78° C. under an inert atmosphere. The solution was stirred at -70° c. for 15 min, then 4,4,4-trifluorobutyryl chloride (320 g) was added over 30 min at -60° C. and the mixture warmed to room temperature and stirred overnight. The mixture was evaporated and the residue was partitioned between diethyl ether and water. The ethereal layer was washed (1N hydrochloric acid, brine (twice)), dried (MgSO4), and evaporated to yield crude product (604 g, about 100%). Filtration through 3000 ml of silica gel using 1:1 methylene chloride:hexanes as the eluent afforded a white solid. Recrystallization from methylene chloride:hexanes afforded (4R,5S)-4-methyl-3-(4,4,4-trifluorobutyryl)-5-phenyl-2-oxazolidinone (519 g, 86%); m.p. 93°-95° C.; partial NMR (300 MHz, CDCl3): 0.91 (d, 3H, CH3), 2.45-2.65 (m, 2H, CF3CH2), 3.18-3.40 (m, 2H, CH2CO), 4.78 (m, 1H, 4-H oxazolidinone), 5.70 (d, 1H, 5-H oxazolidone), 7.30-7.44 (m, 5H, Ar).

Provenance & Evidence