O-(Benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium tetrafluoroborate → (2r)-{[(2r)-2-({[4-((2r,3r)-1-(4-Fluorophenyl)-3-{[2-(4-fluorophenyl)-2-hydroxyethyl]thio}-4-oxoazetidin-2-yl)phenoxy]acetyl}amino)-2-phenylacetyl]amino}(phenyl)acetic acid

Participants

Reaction Steps

(2R)-({[4-((2R,3R)-1-(4-Fluorophenyl)-3-{[2-(4-fluorophenyl)-2-oxoethyl]thio}-4-oxoazetidin-2-yl)phenoxy]acetyl)amino)(phenyl)acetic acid (0.040 g, 0.065 mmol) was dissolved in CH2Cl2 (5 ml) and tert-butyl (2R)-amino(phenyl)acetate (0.016 g, 0.078 mmol) and N-methyl-morphiline (0.020 g, 0.195 mmol) were added. After 5 minutes TBTU (0.027 g, 0.084 mmol) was added. The reaction was allowed to stir at room temperature for 3 h after which the resulting tert-butyl ester was purified on silica gel and eluted with EtOAc/CH2Cl2 25/75. Pure fractions were concentrated. The residue was dissolved in CH2Cl2 (3 ml) and TFA (0.5 ml). The reaction mixture was allowed to stir overnight at room temperature. The resulting acid was concentrated and the remaining trace of TFA was removed by co-evaporation with toluene (3 ml). The acid was dissolved in MeOH (3 ml) and NaBH (0.010 g, 0.260 mmol) was added. After 5 minutes, full conversion to the corresponding alcohol was obtained. The reaction was quenched by the addition of 1 ml of 0.1M NH4OAc buffer. Concentration followed by purification on preparative HPLC using a gradient of 20-50% CH3CN in 0.1M NH4OAc buffer as mobile phase and freeze-drying of the pure fractions afforded the title compound (0.034 g, 70%) as a colourless solid. M/z: 750.4 (M−1). 1H NMR [(CD3)2SO), 400 MHz] δ 2.88-2.94 (m, 2H), 4.23-4.29 (m, 1H), 4.56-4.65 (m, 2H), 4.70-4.78 (m, 1H), 4.91-5.06 (m, 2H), 5.65-5.75 (m, 1H), 6.93-7.42 (m, 22H), 8.54-8.69 (m, 2H).

Provenance & Evidence