Cl.[NH:2]1[CH2:5][CH:4]([OH:6])[CH2:3]1.[CH:7]1([CH:12]([NH:16][C:17]([O:19][CH3:20])=[O:18])[C:13](O)=[O:14])[CH2:11][CH2:10][CH2:9][CH2:8]1.CCN(C(C)C)C(C)C.OS([O-])(=O)=O.[K+]>C(Cl)Cl.CN(C(ON1N=NC2C=CC=CC1=2)=[N+](C)C)C.[B-](F)(F)(F)F>[CH:7]1([CH:12]([NH:16][C:17](=[O:18])[O:19][CH3:20])[C:13]([N:2]2[CH2:5][CH:4]([OH:6])[CH2:3]2)=[O:14])[CH2:8][CH2:9][CH2:10][CH2:11]1TBTU (0.373 g, 1.16 mmol) was added to azetidin-3-ol hydrochloride (1.960 g, 17.89 mmol), 2-cyclopentyl-2-(methoxycarbonylamino)acetic acid (Compound J2.1) (3 g, 14.91 mmol) and DIPEA (10 mL, 57.3 mmol) in DCM (60 mL) at rt. The resultant mixture was stirred for 2 h. Additional azetidin-3-ol hydrochloride (0.45 g, 4.11 mmol) was added and the mixture was heated at 50° C. for 1.5 h. The mixture was cooled to rt and the pH was adjusted to 2 using KHSO4 (1.5 M). The mixture was extracted with DCM and the combined DCM layers were washed with brine and concentrated under reduced pressure. The residue was diluted with MeOH (15 mL) and KOH (1.56 g) in water (30 mL) was added. The resultant mixture was stirred at rt for 5 h. Part of the solvent was removed under reduce pressure. The remaining mixture was diluted with water and extracted with DCM. The organic layer was washed with brine, dried (MgSO4) and concentrated under reduce pressure. The residue was purified via Biotage (gradient: 10-100% of DCM/MeOH (1:0.05) in DCM, KP-SIL 100 g column) to give the title product (5.95 g, 50%). 1H NMR (600 MHz, CDCl3) 1.15-1.40, 1.45-1.81, 2.04-2.20, 2.33, 2.50, 3.65, 3.84, 3.92, 4.04, 4.14-4.28, 4.32, 4.37-4.44, 4.65, 5.25. Total no of protons: 20.
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