Triethylamine → 1-((Tert-butoxy)carbonyl)pyrrolidine-3-carboxylic acid

Participants

Reaction Steps

A solution of 205 g. (1 mol.) of N-benzylpyrrolidine-3-carboxylic acid (CA, 64 14173d) is dissolved in glacial acetic acid (1 l.) and hydrogenated in the presence of 40 g. of 10% palladium on charcoal until no more starting material is detected by TLC. The catalyst is filtered off and the filtrate is concentrated to dryness in vacuo. The residual 3-pyrrolidine carboxylic acid is dissolved in a mixture of DMF-H2O (2:1) (2 liters), triethylamine (1 mol.), t-butoxycarbonyl azide (1.5 mol.) is added and the mixture is stirred at room temperature for two days. Periodically the pH is tested with pH paper, and after twenty-four hours more azide (0.5 mol.) is added. The solvent is concentrated in vacuo to remove the DMF, the aqueous phase is acidified with citric acid (to pH 2-3) and extracted with ethyl acetate. The organic phase is concentrated to dryness in vacuo to yield the product 1-(t-butyloxycarbonyl)-3-pyrrolidinecarboxylic acid.

Provenance & Evidence