[C:1]([O:5][C:6]([NH:8][CH2:9][C:10]1[CH:15]=[CH:14][C:13]([CH2:16][CH2:17][C:18]([OH:20])=O)=[CH:12][CH:11]=1)=[O:7])([CH3:4])([CH3:3])[CH3:2].C(N(CC)CC)C.CN(C(ON1N=NC2C=CC=CC1=2)=[N+](C)C)C.F[P-](F)(F)(F)(F)F.Cl.[CH3:53][O:54][C:55](=[O:64])[C@@H:56]1[CH2:60][C@H:59]([N:61]=[N+:62]=[N-:63])[CH2:58][NH:57]1>CN(C=O)C.O.C(OCC)(=O)C>[CH3:53][O:54][C:55](=[O:64])[C@@H:56]1[CH2:60][CH:59]([N:61]=[N+:62]=[N-:63])[CH2:58][N:57]1[C:18](=[O:20])[CH2:17][CH2:16][C:13]1[CH:12]=[CH:11][C:10]([CH2:9][NH:8][C:6]([O:5][C:1]([CH3:2])([CH3:3])[CH3:4])=[O:7])=[CH:15][CH:14]=12.70 g (9.5 mmol) of 3-(4-tert-butyloxycarbonylaminomethylphenyl)propionic acid (starting compound A6) are dissolved in 40 ml of DMF, and 2.7 ml of triethylamine are added. After stirring for 5 min., 3.63 g of HBTU are added and, after a further 5 min., 2 g of (2S,4S)-4-azidoproline methyl ester hydrochloride. Stirring at RT overnight is followed by addition of ethyl acetate and water and separation of the phases. The organic phase is washed once each with 1N sodium hydroxide solution, 1N hydrochloric acid solution, saturated sodium bicarbonate solution and saturated brine. Drying over magnesium sulfate is followed by concentration and drying under high vacuum. 4.1 g of the title compound are obtained as a pale orange oil. The mass spectrum shows the molecular peak MNH4+ at 449 Da.
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