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

Participants

Reaction Conditions

Reaction Steps

A further batch of N-benzyl-3-(S)-(4-fluorophenyl)-1,4-oxazin-2-one (-)-3BCS salt was prepared substantially according to the previous method except that the following quantities and reaction conditions were used: N-benzyl-3-(4-fluorophenyl)-1,4-oxazin-2-one (racemate) (4.96 g); (-)-3BCS in acetonitrile (1.85M; 9.4 ml); trifluoroacetic acid (2.1 ml); and isopropyl acetate (55 ml). The mixture was stirred at 90° C. for 6 days and then cooled to 0°-5° C. and aged for 1 hour. The solid N-benzyl-3-(S)-(4-fluorophenyl)-1,4-oxazin-2-one (-)-3BCS salt was collected and washed with isopropyl acetate (20 ml). Yield 9.40 g (90%); ee 99.6% (S) isomer. The chiral composition of the remaining liquors was determined as 88% (R), 12% (S).

Provenance & Evidence