Phosphate → (6z)-6-(5h-Imidazo[2,1-a]isoindol-2-ylmethylene)-7-oxo-4-thia-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid sodium salt

Participants

Reaction Steps

(5R, 6RS)-6-[(RS)-Acetoxy-(5H-imidazo[2,1-a]isoindol-2-yl)-methyl]-6-bromo-7-oxo-4-thia-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylic acid 4-nitro-benzyl ester (1.5 g) was dissolved in THF (21 mL) and acetonitrile (9.8 mL). Freshly activated Zn dust (6 g) and 0.5 M phosphate buffer (pH 6.4, 30.8 mL) were added to the reaction mixture. The reaction vessel was covered with foil to exclude light. The mixture was vigorously stirred for 2 h at room temperature. The mixture was cooled to 9° C., and 1 M NaOH aqueous solution was added to adjust pH to 7.5. The reaction solution was mixed with ethyl acetate and filtered through a pad of Celite. The pad was washed with water and the aqueous layer was separated. The aqueous layer was concentrated to 25 mL under high vacuum at 35° C. The concentrate was applied to Diaion HP-21 (100 mL, Mitsubishi Kasei Co. Ltd.) resin column chromatography. After adsorbing, the column was eluted with water and then with 5–15% acetonitrile-water. The combined fractions was concentrated under high vacuum at 35° C. and lyophilized to give the title compound as a yellow amorphous solid (527 mg, 58%). Mp 170° C. (dec); 1H NMR (400 MHz, D2O) δ 4.62 (s, 2H), 6.27 (s, 1H), 6.56 (s, 1H), 6.78 (s, 1H), 7.22–7.31 (m, 4H), 7.52 (d, 1H, J=6.7 Hz).

Provenance & Evidence