A solution of 166 mg (1.02 mmol) of 1,1′-carbonyldiimidazole in 8 ml of DMF was mixed with 515 mg (1.02 mmol) of the trifluoroacetate from step B and 0.57 ml (415 mg, 4.10 mmol) of triethylamine. A solution of 328 mg (1.02 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 8 ml of DMF was added to this mixture under argon, and the mixture was stirred at RT overnight. The reaction mixture was then concentrated and separated by preparative HPLC. The required fractions were combined and freed of acetonitrile. The resulting aqueous solution was extracted with ethyl acetate, and the organic phase was dried over sodium sulfate, filtered and concentrated. 222 mg of the title compound were obtained.
