(3R,5S)-7-Oxo-4-oxa-1-azabicyclo[3.2.0]heptane-3-carboxylic acid is a key bicyclic β-lactam intermediate. Its structure features a fused oxazolidine and β-lactam ring system, which is a core scaffold found in several important carbapenem antibiotics. This compound serves as a crucial advanced intermediate in the synthesis of broad-spectrum carbapenem antibiotics, most notably ertapenem. Ertapenem is a once-daily parenteral carbapenem used to treat moderate to severe infections caused by susceptible bacteria, including complicated intra-abdominal infections, skin and skin structure infections, and community-acquired pneumonia. The specific (3R,5S) stereochemistry of this intermediate is essential for conferring the desired biological activity and stability to the final drug molecule. As a high-value pharmaceutical intermediate, its production and quality control are critical steps in the manufacturing process of final active pharmaceutical ingredients (APIs). Its synthesis and application are primarily within the domain of specialized pharmaceutical chemistry and process development.