Acetic Anhydride → 6-[acetoxy-(4H,10H-pyrazolo[-5,1-c][1,4]benzoxazepine-8-yl)-methyl]-6-bromo-7oxo-4-thia-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid 4-nitro-benzyl ester

Participants

Reaction Conditions

Reaction Steps

4H,10H-pyrazolo[5,1-c][1,4]benzoxazepine-2-carbaldehyde (0.19 g, 0.887 mmol) in acetonitrile (14 ml) was added to MgBr2 (0.49 g, 2.66 mmol) under N2. After 25 minutes 6-Bromo-7-oxo-4-thia-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid 4-nitro-benzyl ester (0.342 g, 0.888 mmol.) in THF (14 ml) was added. After 15 minutes the reaction was cooled to −20° C. Ten minutes later added Et3N (3eq) and placed reaction in the dark. After 6.5 hours added Ac2O (0.42 ml, 4.45 mmol) and DMAP (0.011 g, 0.0900 mmol). Warmed to 0° C. and placed in freezer overnight. Reaction solution was concentrated and resulting residue was taken up in EtOAc. Washed with 5% citric acid(aq) and saturated NaHCO3(aq). Further washed with water and brine. Dried organics over sodium sulfate and filtered and concentrated. Purified with silica gel prep plates and 1:2 EtOAc/Hexane. Obtained the condensation product (yellow gum/solid). Yield: 0.31 g, 54% yield.

Provenance & Evidence