This compound, with CAS number 51857-11-5, is the potassium salt of a penem derivative. Its complex chemical name, [2S-(2α,5α,β)]-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-carboxylic acid, reveals its core structure as a β-lactam antibiotic belonging to the penem class, which is structurally related to both penicillins and carbapenems. The presence of the bicyclic β-lactam ring system is essential for its antibacterial activity. The primary and definitive application of this compound is as an active pharmaceutical ingredient (API) in the field of anti-infective therapeutics. Specifically, it is a key intermediate or the final salt form of Fropenem (also known as Faropenem), a broad-spectrum oral antibiotic. Fropenem is used clinically to treat various bacterial infections, including respiratory tract, urinary tract, and skin/soft tissue infections, by inhibiting bacterial cell wall synthesis. As a potassium salt, this form likely offers improved solubility and stability characteristics for pharmaceutical formulation compared to the free acid. Its classification and use are strictly within the domain of medicinal chemistry for antibiotic development and production, with no significant role as a general-purpose synthetic building block in other chemical fields.