4-Methylmorpholine → n-{[4-((2r,3r)-1-(4-Chlorophenyl)-3-{[2-(4-chlorophenyl)-2-hydroxyethyl]thio}-4-oxoazetidin-2-yl)phenoxy]acetyl}glycyl-d-valine

Participants

Reaction Steps

[4-((2R,3R)-1-(4-Chlorophenyl)-3-{[2-(4-chlorophenyl)-2-oxoethyl]thio}-4-oxoazetidin-2-yl)phenoxy]acetic acid (15.3 mg, 0.03 mmol), N-methylmorpholine (10 μl, 0.091 mmol) and tert-butyl glycyl-D-valinate hydrochloride, (10.4 mg, 0.039 mmol) were dissolved in DCM (2 ml). After 10 minutes, TBTU (11.9 mg, 0.037 mmol) was added and the mixture was stirred overnight. The intermediate tert-butylester was confirmed. M/z: 727.8 (M−H). The reaction mixture was extracted between water (10 ml, acidified to pH of 3 with KHSO4 (2M)) and DCM (3×10 ml). The combined organic phases were washed with water (2×20 ml), dried over Na2SO4, filtered and concentrated. The oily residue was dissolved in DCM (2 ml) and TFA (1.3 ml) was added. The mixture was stirred overnight. The solvent was evaporated and co-evaporation with toluene was performed to assist the removal of TFA. The residue was dissolved in methanol (2 ml) and sodium borohydride (12.3 mg, 0.33 mmol) was added. After 15 minutes, ammonium acetate (17 mg) was added and the solvent was removed under reduced pressure. The residue was purified on preparative HPLC on C8 column. A gradient from 20% to 50% MeCN in 0.1M ammonium acetate buffer was used as eluent. After lyophilisation, the title compound was obtained as a white solid (15.1 mg, 77%). H-NMR (400 MHz, DMSO-d6): 0.78 (d, 3H), 0.80 (d, 3H), 0.95-1.03 (m, 1H), 2.83-3.00 (m, 2H), 3.75-3.80 (m, 2H), 3.93-4-00 (t, 1H), 4.30 (d, 0.5H), 4.36-4.38 (brs, 0.5H), 4.52 (s, 2H), 4.69-4.77 (m, 1H), 5.02 (d, 0.5H), 5.06 (d, 0.5H), 6.96-7.00 (m, 2H), 7.18-7.22 (m, 2H), 7.31-7.38 (m, 8H), 7.60-7.74 (m, 1H), 8.28 (t, 1H). M/z: 671.9 (M+H).

Provenance & Evidence