(6R-(6alpha,7beta))-3-(((1-Methyl-1H-tetrazol-5-yl)thio)methyl)-8-oxo-7-(phenylacetamido)-5-thia-1-azabicyclo(4.2.0)oct-2-ene-2-carboxylic acid 5-oxide 81589-25-5 EINECS 279-784-3