Formaldehyde → 3-{3-[(Benzyloxy)carbonyl]-5-oxo-1,3-oxazolidin-4-yl}propanoic acid

Participants

Reaction Steps

To 300 ml of toluene were added 100 g of DL-N-benzyloxycarbonylglutamic acid, 20 g of powdery paraformaldehyde and 4 g of p-toluenesulfonic acid monohydrate, and the resulting mixture was subjected to azeotropic dehydration for 3 hours. Subsequently, the solvent was removed by distillation under reduced pressure, and the oily product thus obtained was dissolved in 200 ml of ethyl acetate, after which the resulting solution was washed with water. The organic layer thus formed was then separated and dried over anhydrous magnesium sulfate, and the solvent was removed by distillation under reduced pressure to obtain oily DL-3-benzyloxycarbonyl-4-(2-carboxyethyl)oxazolidin-5-one. Thus product was dissolved in 250 ml of toluene with heating, and 120 g of n-propylamine was added thereto, after which the resulting mixture was heated under reflux for 3.5 hours. Subsequently, the solvent was removed by distillation under reduced pressure, and the resulting residue was dissolved in 250 ml of ethyl acetate, after which the resulting solution was washed with three 100-ml portions of diluted hydrochloric acid. The resulting organic layer was separated, and the pH thereof was adjusted to 10 with a 3% aqueous sodium hydroxide solution, after which the resulting aqueous layer was separated. The pH of the aqueous layer was adjusted to 6 with diluted hydrochloric acid, and the crystals thus precipitated were collected by filtration to obtain 87 g (yield 76%) of DL-N2 -benzyloxycarbonyl-N1 -n-propyl-α-glutamylamide having a melting point of 132°-135° C.

Provenance & Evidence