Ethylmorpholine → HCID 13341543, compound

Participants

Reaction Steps

A stirred solution of 3.45 g of tert.butyl 2-(5-carboxy-2-phthalimidobutyryl)-3-pyrazolidinecarboxylate and 0.92 g of N-ethylmorpholine in 50 ml of dry tetrahydrofuran was cooled to 0° C. and treated with 1.66 g of phosphorus pentachloride. After 1 hour, a further 0.92 g of N-ethylmorpholine and 1.66 g of phosphorus pentachloride were added and, after a further 1 hour, another 0.92 g of N-ethylmorpholine was added. The solvent was removed by evaporation and the residue was partitioned between water and ethyl acetate. The organic layer was washed with saturated aqueous sodium bicarbonate solution, dried over magnesium sulphate and evaporated. The oil obtained was chromatographed on silica gel. Elution with diethyl ether yielded firstly 1.1 g (33%) of tert.butyl 2,3,6,7,8,9-hexahydro-5,9-dioxo-8(S)-phthalimido-1H,5H-pyrazolo[1,2-α][1,2]diazepine-1(S)-carboxylate in the form of a white foam and then 0.52 g (15%) of tert.butyl 2,3,6,7,8,9-hexahydro-5,9-dioxo-8(S)-phthalimido-1H,5H-pyrazolo[1,2-a][1,2]diazepine-1(R)-carboxylate in the form of a white solid of melting point 180°-181° C. (from ethyl acetate/n-hexane).

Provenance & Evidence