Ethylmorpholine → 1-[2(R)-[1(R)-(benzyloxycarbamoyl)-2-(3,4,4-trimethyl-2,5-dioxo-1-imidazolidinyl)ethyl]-3-cyclopentylpropionyl)piperidine

Beteiligte Stoffe

Reaktionsschritte

0.74 g of N-ethylmorpholine, 0.60 g of hydroxybenzotriazole hydrate and 0.75 g of N-ethyl-N′-(3-dimethylaminopropyl)-carbodiimide were added at 0° in succession to a solution of 1.38 g of 1-[2(R)-[1(R)-carboxy-2-(3,4,4-trimethyl-2,5-dioxo-1-imidazolidinyl)ethyl]-3-cyclopentylpropionyl)piperdine VI in 13 ml of methylene chloride and the mixture was stirred at 0° for 20 min. The reaction mixture was treated with 0.45 g of N-ethylmorpholine and 0.63 g of O-benzylhydroxylamine hydrochloride and stirred at 0° for 30 min. and at 22° for 17 hrs. The solution was diluted with 13 ml of methylene chloride, washed with sodium bicarbonate solution and dilute hydrochloric acid, dried and concentrated. The residue was crystallized from ethyl acetate/hexane and the crystallizate was dried, there being obtained 1.26 g (73%) of pure 1-[2(R)-[1-(R)-(benzyloxycarbamoyl)-2-(3,4,4-trimethyl-2,5-dioxo-1-imidazolidinyl)ethyl]-3-cyclopentylpropionyl)piperidine VII, m.p. 138-140°.

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