Trifluoroacetic acid → N-{[4-((2R,3R)-1-(4-Fluorophenyl)-3-{[2-(4-fluorophenyl)-2-hydroxyethy]thio}-4-oxoazetidin-2-yl)phenoxy]acetyl}-L-alanyl-D-valine

Participants

Reaction Steps

A solution of N-{[4-((2R,3R)-1-(4-fluorophenyl)-3-([2-(4-fluorophenyl)-2-oxoethyl]thio}-4-oxoazetidin-2-yl)phenoxy]acetyl}-L-alanine (0.015 g, 0.027 mmol), D-valine tert-butyl ester hydrochloride (0.008 g, 0.038 mmol) and N-methylmorpholine (0.030 ml, 0.272 mmol) in DCM (4 ml) was stirred for 5 min. TBTU (0.013 g, 0.041 mmol) was added. After 3 h, the conversion to the ester (M/z: 710.2) was completed and TFA (3 ml) was added. After 4 h, the mixture was diluted with toluene (2 ml) and the solvent was removed under reduced pressure. The residue was dissolved in MeOH (4 ml) and NaBH4 was added in small portions to the solution (a total of 0.065 g, 1.72 mmol) until the reduction was complete. Ammonium acetate buffer (0.1M, 3 ml) was added and most of the methanol was removed under reduced pressure. The remaining solution was purified by preparative HPLC, using a gradient of 20-50% MeCN in a 0.1M ammonium acetate buffer as eluent. After freeze-drying, 0.014 g (77% yield) of the title compound was obtained as a white solid. M/z: 656.1. 1H NMR (DMSO, 400 MHz): δ 0.75-0.83 (m, 6H), 1.22 (d, 3H), 1.95-2.07 (m, 1H), 3.83-3.96 (m, 2H), 3-98-4.06 (m, 1H), 4-24-4.31 (m, 1H), 4.40-4.54 (m, 3H), 4.67-4.76 (m, 1H), 5.01-5.07 (m, 1H), 6.91-7.98 (m, 2H), 7.05-7.17 (m, 4H), 7.19-7.25 (m, 2H), 7.29-7.39 (m, 4H), 7.84-7.95 (m, 1H). 8.07 (d, 1H),

Provenance & Evidence