Triethylamine → tert-butyl(S)-3-(6-tert-butoxycarbonylaminopyridin-3-yl)-2-[3-((9S,12R)-9-isopropyl-11-oxo-2,7-dioxa-10-azabicyclo[12.2.2]octadeca-1(17),14(18),15-trien-12-yl)ureido]propionate

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Reaction Steps

112 mg (0.69 mmol) of 1,1′-carbonyldiimidazole were added to a mixture of 234 mg (0.69 mmol) of tert-butyl(S)-2-amino-3-(6-tert-butoxycarbonylaminopyridin-3-yl)-propionate and 106 μl (77 mg, 0.76 mmol) of triethylamine in 2.5 ml of DMF. The solution was stirred at RT for 1 h, before a solution of 222 mg (0.69 mmol) of (9S,12R)-12-amino-9-isopropyl-2,7-dioxa-10-azabicyclo[12.2.2]octadeca-1(17),14(18),15-trien-11-one (1-1E) in 2.5 ml of DMF was added. The mixture was left to stand overnight and then concentrated and partitioned between water and ethyl acetate. The organic phase was separated off, dried over sodium sulfate, filtered and concentrated. The residue was purified by preparative HPLC. The required fractions were combined, freed of acetonitrile, made slightly alkaline with sodium bicarbonate and extracted with ethyl acetate. The organic phase was dried over sodium sulfate, filtered and concentrated.

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