6-carboxy-N2-[[[carboxy-2-[(1-oxoheptyl)amino]ethyl]amino]carbonyl]-N6-[(1,1-dimethylethoxy)carbonyl]-L-lysyl-D-alanine → N-[6-carboxy-N2-[[[2-carboxy-2-[(1-oxoheptyl)amino]-ethyl]amino]carbonyl]-L-lysyl]-D-alanine

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Reaction Steps

To 85.9 mg of 1b-5 under argon is treated with 500 μl of TFA according to Example 80. The volatiles are evaporated to a residue which is triturated with ether 3× and the ether is decanted. The residue is dried to give 77.9 mg of 1b-11 as a white solid. NMR (CD3OD) δ 0.80 (t, 3 H), 2.16 (t, 2 H), 3.22 (br s, 5 H), 3.58 (m, 2 H), 3.85 (m, 1 H), 4.15 (m, 1 H), 4.30 (d, 1 H), 4.40 (m, 1 H); MS (HR-FAB) m/z 526.2482 (M+H, calcd for C21H38N5O9 526.2489).

Provenance & Evidence