3,4-Dichlorophenyl isocyanate → (R)-4-[3-((S)-4-Hydroxy-6-aza-spiro[2.5]oct-6-yl)-propyl]-2-methyl-5-oxo-[1,4]diazepane-1-carboxylic acid (3,4-dichloro-phenyl)-amide

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Reaction Steps

A solution of 0.120 g (purity: 76% corresponds to 0.25 mmol) of (R)-4-[3-((S)-4-hydroxy-6-aza-spiro[2.5]oct-6-yl)-propyl]-2-methyl-[1,4]diazepan-5-one dihydrochloride (example 1E) in 2 ml N,N-dimethylformamide was treated at room temperature with 0.052 g (0.27 mmol, 1.1 eq.) of 3,4-dichlorophenyl isocyanate and 0.136 ml (1.24 mmol, 5 eq.) of 4-methylmorpholine. The reaction was stirred at room temperature overnight. To the solution was added 5 mg (0.02 mmol, 0.1 eq.) of 3,4-dichlorophenyl isocyanate. After 1 h, no starting material was left; the solution was slowly added to a solution of sat. aq. sodium hydrogencarbonate, followed by extraction with ethyl acetate (3 times). The organic phases were washed with a solution of sat. aq. sodium hydrogencarbonate and with 10% aq. sodium chloride solution. The combined organic phases were dried over Na2SO4 and the solvent was removed under vacuum. The crude product was purified by flash chromatography (20 g SiO2-column, dichloro-methane/methanol 2:98, 5:95, 1:9, 1:4) to give 0.061 g (51%) of the title compound as white solid. MS: 483.4 (MH+, 2Cl).

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