4-Methylmorpholine → (R)-1-[6-[(R)-2-ethoxycarbonyl-pyrrolidin-1-yl]-6-oxo-hexanoyl]-pyrrolidine-2-carboxylic acid benzyl ester

Participants

Reaction Steps

A mixture of 403 mg (3.15 mmol) adipic acid anhydride, 604 mg (2.5 mmol) D-proline-benzyl-ester hydrochloride and 274 ml (2.5 mmol) N-methyl-morpholin in 10 ml dichloromethane was stirred at room temperature for 1 hour. Then 0.5 g polymer bound primary amine (2 meq/g) were added and stirring was continued for 1 hour. After filtration 823 ml (7.5 mmol) N-methyl-morpholin, 338 mg (2.5 mmol) 1-hydroxybenzotriazole, 479 mg (2.5 mmol) 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 450 mg (2.5 mmol) D-proline-ethyl-ester were added and the mixture was stirred for another 48 hours. Removal of the solvent and chromatography on silicagel with ethylacetate gave 135 mg (12%) (R)-1-[6-[(R)-2-ethoxycarbonyl-pyrrolidin-1-yl]-6-oxo-hexanoyl]-pyrrolidine-2-carboxylic acid benzyl ester as a light yellow oil, MS m/e (%): 459 (M+H+, 100).

Provenance & Evidence