Triphenylphosphine → (2R,4S)-4-fluoro-2-(2-oxo-ethyl)-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester 2-methyl ester
Reaction equation
[CH3:1][O:2][C:3]([C@@:5]1([CH2:18][CH:19]=C)[CH2:9][C@H:8]([F:10])[CH2:7][N:6]1[C:11]([O:13][C:14]([CH3:17])([CH3:16])[CH3:15])=[O:12])=[O:4].C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.ClCCl.C[OH:44]>>[CH3:1][O:2][C:3]([C@@:5]1([CH2:18][CH:19]=[O:44])[CH2:9][C@H:8]([F:10])[CH2:7][N:6]1[C:11]([O:13][C:14]([CH3:15])([CH3:16])[CH3:17])=[O:12])=[O:4]Participants
4
Conditions
- Temperature
- -78 °C
Procedure
1 g (3.5 mmol) (2R,4S)-2-allyl-4-fluoro-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester 2-methyl ester is dissolved in 60 mL dichloromethane/methanol 1:1, cooled to −78° C., flushed with oxygen for two minutes then treated with a flux of ozone until the solution turns light blue. The solution is allowed to warm up to room temperature after addition of 1 g (1.1 eq.) triphenylphosphine, stirred an additional 5 h and column chromatographed (silica gel, TBME/petroleum ether 3:2) to yield 870 mg of the desired product as a clear oil.