4-Methylmorpholine → N-[(1,1-Dimethylethoxy)carbonyl]-D-alanine 2,5-dioxo-1-pyrrolidinyl ester

Participants

Reaction Conditions

Reaction Steps

To a mixture of Compound (1) (674 mg.) and N-methylmorpholine (202 mg.) in dichloromethane (30 ml.), there was added isobutyl chloroformate (273 mg.) at -15°--20° C. and the mixture was stirred for 30 minutes at the same temperaure. The mixture was cooled to -40° C., and to this, there was added trimethyl silyl ester of Compound (2), which was prepared from Compound (2) (910 mg.) and bis(trimethylsilyl)acetamide (3 ml.) by stirring in a mixture of dichloromethane (20 ml.) and N,N-dimethylformamide (2 ml.). This mixture was stirred for 1 hour at -15°--20° C., and after evaporation of the solvent, the residue was dissolved in ethylacetate (100 ml.), and then the solution was washed successively with 2%--HCl and water, dried over MgSO4 and evaporated. The residue was pulverized with isopyropyl ether to give Compound (3) (1.25 g.).

Provenance & Evidence