N-benzyl-4-fluorophenyl-1,4-oxazin-2-one → N-benzyl-3-(S)-(4-fluorophenyl)-1,4-oxazin-2-one

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Reaction Steps

A solution of N-benzyl-4-fluorophenyl-1,4-oxazin-2-one (5 g) in isopropyl acetate (16.76 ml) was diluted with isopropyl acetate (37.6 ml) and a solution of (-)-3-bromocamphor-8-sulphonic acid ((-)-3-BCS) (5.73 g) in isopropyl acetate (20.67 ml) added at room temperature. Crystallisation began after approximately 20 minutes. The mixture was stirred for 1 hour at room temperature and then stirred at 75° C. for 9 days. The mixture was then cooled to room temperature, aged at 0°-5° C. for 1 hour and the solid collected, washed with isopropyl acetate to give the N-benzyl-3-(S)-(4-fluorophenyl)-1,4-oxazin-2-one (-)-3-BCS salt: yield 10.5 g, ee 96.5% (S) isomer.

Provenance & Evidence