Ethylmorpholine → 2(R)-[1(S)-(tert-butoxycarbonyl)-4-phenylbutyl]-N-(4(S)-isopropyl-2,5-dioxo-1-imidazolidinyl)-4-methylvaleramide

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Reaction Steps

A solution of 0.517 g of 2(R)-[1(S)-(tert-butoxycarbonyl)-4-phenylbutyl]-4-methylvalerohydrazide in 5 ml of dichloromethane was treated with 0.302 g of methyl (S)-(+)-2-isocyanato-3-methylbutyrate and 0.3 ml of N-ethylmorpholine. The mixture was stirred at room temperature for 4 hours and then the solution was washed with 5% aqueous citric acid solution, saturated sodium chloride solution, dried over anhydrous magnesium sulphate and evaporated. The residue was dissolved in 5 ml of toluene containing 0.2 ml of triethylamine. The mixture was heated at reflux for 24 hours. The solution was cooled, diluted with ethyl acetate and washed with 5% aqueous citric acid solution, saturated sodium chloride solution, dried over anhydrous magnesium sulphate, and evaporated. The residue was triturated with ether and there was obtained 0.468 g of 2(R)-[1(S)-(tert-butoxycarbonyl)-4-phenylbutyl]-N-(4(S)-isopropyl-2,5-dioxo-1-imidazolidinyl)-4-methylvaleramide in the form of a white solid.

Provenance & Evidence