[OH:1][C@@H:2]1[CH2:5][C@H:4]([CH2:6][NH:7][C:8](=[O:14])[O:9][C:10]([CH3:13])([CH3:12])[CH3:11])[CH2:3]1.C(N(CC)CC)C.[CH3:22][S:23](Cl)(=[O:25])=[O:24].O>C(Cl)Cl>[CH3:22][S:23]([O:1][C@H:2]1[CH2:5][C@@H:4]([CH2:6][NH:7][C:8]([O:9][C:10]([CH3:11])([CH3:13])[CH3:12])=[O:14])[CH2:3]1)(=[O:25])=[O:24]Intermediate 29, tert-Butyl [(cis-3-Hydroxycyclobutyl)methyl]carbamate (5.15 g, 26 mmol) and triethylamine (8.9 mL, 61 mmol) were dissolved in CH2Cl2 (50 mL). MsCl (2.4 mL, 31 mmol) was added dropwise at −20° C. under stirring in argon. The temperature was brought to ambient within 1 h. Water (100 mL) was added, and the layers were separated. The organic one was washed with water, brine, dried with Na2SO4, and evaporated, to give the title compound (5 g, 70%) white crystals. This crude product was used for the next stage without additional purification. 1H NMR-data (DMSO-d6): 6.74-7.00 (m, 1H, NH); 4.73-4.86 (m, 1H); 3.10 (s, 3H, MS); 2.97 (t, 2H, CH2, J=5.7 Hz); 2.32-2.42 (m, 2H); 1.80-2.43 (m, 3H); 1.38 (s, 9H, Boc).
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