(2S,5R,6R)-6-[[(2R)-[(3-Methoxy-1-methyl-3-oxo-1-propenyl)amino]phenylacetyl]amino]-3,3-dimethyl-7-oxo-4-Thia-1-azabicyclo[3.2.0]heptane-2-carboxylic Acid Triethylamine