Reaction #9987

Reaction equation

Potassium t-butoxide

(S)-1-benzyloxycarbonyl-4-oxoproline methyl ester

ammonium chloride

→

title compound

Yield 72.6%

(S)-1-Benzyloxycarbonyl-4-methylideneproline methyl ester

Yield 72.6%

Solvents

diethyl ether

diethyl ether

Conditions

Workup

1. 1
   workup.STIRRINGthe resulting mixture was stirred at 35° C. for 3 hours
2. 2
   Otherpartitioned
3. 3
   WashThe organic layer was washed with water
4. 4
   Dryingdried over anhydrous magnesium sulfate
5. 5
   Otherthe solvent was removed by distillation under reduced pressure
6. 6
   OtherThe residue was purified by column chromatography through silica gel (eluent, ethyl acetate:hexane=1:3)

Procedure

Potassium t-butoxide (1.41 g, 12.6 mmol) was suspended in diethyl ether (100 ml). To the suspension was added methyltriphenylphosphonium bromide (4.80 g, 13.4 mmol), and the resulting mixture was stirred at 5° C. for 15 minutes. To the mixture was added (S)-1-benzyloxycarbonyl-4-oxoproline methyl ester (2.50 g, 9.0 mmol) in diethyl ether (30 ml), and the resulting mixture was stirred at 35° C. for 3 hours. At the end of this time, the reaction mixture was added to a saturated solution of ammonium chloride (50 ml) under ice cooling, and then partitioned. The organic layer was washed with water, dried over anhydrous magnesium sulfate and the solvent was removed by distillation under reduced pressure. The residue was purified by column chromatography through silica gel (eluent, ethyl acetate:hexane=1:3), to give the title compound (1.80 g) as a pale yellow oil (yield 72%).

Source