(2S,5β)-6α-[[(R)-[(3-Methoxy-1-methyl-3-oxo-1-propenyl)amino]phenylacetyl]amino]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2β-carboxylic acid potassium salt

potassium [2S-[2alpha,5alpha,6beta(S*)]]-6-[[[(3-methoxy-1-methyl-3-oxoprop-1-enyl)amino]phenylacetyl]amino]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate