Bromine → HCID 131713496, compound

Participants

Reaction Steps

Sodium (5R,6S)-3-[(E)-2-acetamidoethenylthio]-6-[(S)-1-hydroxyethyl]-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate (200 mg of 52.6% pure material) in water (10 ml) was treated with Aliquat 336 (500 mg) in dichloromethane (10 ml). After separation the aqueous solution was re-extracted with dichloromethane (10 ml) containing Aliquat 336 (500 mg). The dichloromethane extracts were combined, dried (MgSO4) and evaporated in vacuo to leave a mixture of Aliquat 336 and the quaternary ammonium salt corresponding to the starting sodium salt. This mixture was redissolved in dichloromethane (8 ml) cooled to -70° and bromine in carbon tetrachloride (0.50 ml; 100 mg/ml) was added, followed by tiethylamine in dichloromethane (0.30 ml; 100 mg/ml). The mixture was allowed to warm to room temperature, the dichloromethane solution was washed with water (3.5 ml) and extracted with a saturated aqueous solution of NaCl(2×3.5 ml). The sodium chloride extracts were combined and loaded onto a DIAION HP20 column (8×1 cm) and the column eluted with saturated aqueous sodium chloride (10 ml) followed by deionised water. Fractions of the aqueous eluate were monitored by u.v. spectroscopy, and those containing a maximum in absorption at ca 300 nm were combined and evaporated in vacuo to low volume. Ethanol (ca 20 ml) was added and evaporated in vacuo to low volume (5×), on the last evaporation all the solvent was removed. Toluene was added to the residue and evaporated in vacuo (2×) to leave the title compound as a solid (24 mg):λmax (H2O)246(11,300), and 297(8,800 nm). λmax(KBr) 1755, 1680, 1620 cm-1.

Provenance & Evidence