To a solution of (2S)-2-((3S)-3-{[(6-chloro-2-naphthyl)sulfonyl]amino}-2-oxopyrrolidin-1-yl)propanoic acid [Intermediate 29] (0.105 g) in DCM (10 ml) were added 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride (0.152 g), HOBT (0.107 g) and triethylamine (0.222 ml) and the mixture was stirred at room temperature for 30 min. Morpholine (0.07 ml) was added and the resultant mixture stirred at room temperature for 16 h. The mixture was partitioned between DCM and water. The aqueous layer was re-extracted with DCM and the combined, dried (over magnesium sulphate) organic extracts were concentrated under reduced pressure. The residue was purified using SPE (silica, eluting with cyclohexane:ethyl acetate 5:1, and ethyl acetate) to give the title compound (0.1 g) as a white solid.
