Dicyclohexylcarbodiimide → methyl N-benzoylphenylalanyltyrosinate

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Reaction Steps

In 100 ml of a mixture of chloroform-tetrahydrofuran (2:1), were dissolved 5.39 g of N-benzoylphenylalanine, 4.64 g of methyl tyrosinate hydrochloride, 2.02 g of triethylamine and 2.30 g of N-hydroxysuccinimide and the solution was cooled with ice. To the cold solution, 4.12 g of N,N'-dicyclohexylcarbodiimide was added. The mixture was stirred for 3 hours, then allowed to stand at room temperature overnight. The precipitates were removed by filtration and the filtrate was concentrated. The residue was extracted with ethyl acetate and the extract was washed with 2% hydrochloric acid, 4% sodium bicarbonate and water, then dried and concentrated to dryness. The residue was crystallized from ethyl acetate-petroleum ether to give 6.6 g of methyl N-benzoylphenylalanyl-tyrosinate with a mp. 188°-190° C. in a yield of 74%. Analysis, calculated for C26H26O5N2 : C, 69.94; H, 5.87; N, 6.27; found C, 69.56; H, 6.01; N, 6.39.

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