Water → HCID 86739931, compound

Participants

Reaction Conditions

Reaction Steps

A solution of 8.7 g (25 millimoles) of (S)-2,3-bis-(benzoylthio)-propionic acid and 4.8 g (25 millimoles) of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride in 125 ml of a 4:1 mixture of tetrahydrofuran and water was added to 4.4 g (25 millimoles) of tert.-butyl proline (crude product, obtained by hydrogenation of 7.6 g of tert.-butyl Z-proline) in 100 ml of tetrahydrofuran, while cooling at 0° C. The mixture was stirred for 1 hour at 0° C. and then for 1 hour at 20° C., after which it was partitioned between ethyl acetate and water by shaking, and the organic phase was dried with anhydrous sodium sulfate and evaporated down under reduced pressure. Chromatography with 2:1 cyclohexane/ethyl acetate over a column containing deactivated silica gel gave 9.0 g (72%) of tert.-butyl N-[(S)-2,3-bis-(benzoylthio)-propionyl]-proline. The crude product was dissolved in 50 ml of dry dioxane, 50 ml of 6N HCl/dioxane were added and the mixture was left to stand for 1 hour at 20° C. It was partitioned between ethyl acetate and water by shaking, the organic phase was washed twice with water, dried with anhydrous sodium sulfate and evaporated down under reduced pressure and 7.8 g (70%) of N-[(S)-2,3-bis-(benzoylthio)-propionyl]-proline, melting point 155°-158° C. (cyclohexane/ethyl acetate), Rf=0.56 in system I, [α]D20 =+76° (c=1 in chloroform), were obtained.

Provenance & Evidence