4-Hydroxy-α-[[(1Z)-3-methoxy-1-methyl-3-oxo-1-propen-1-yl]amino]-benzeneacetic Acid Anhydride Ethyl Hydrogen Carbonate-d4 is an intermediate used in the synthesis of Amoxicillin-d4 (Major) (A634238), which is a labeled semi-synthetic antibiotic related to Penicllin. Antibacterial.