2-{[(2R)-2-[4-({[(7aR,7R)-7-{[(2R)-2-{[(4-ethyl-2,3-dioxopiperazin-1-yl)carbonyl]amino}-2-(4-hydroxyphenyl)acetyl]amino}-3-{[(1-methyl-1,2,3,4-tetraazol-5-yl)sulfanyl]methyl}-6-oxo-2,6,7,7a-tetrahydroazeto[2,1-b][1,3]thiazin-4-yl]carbonyl}oxy)phenyl]-2-{[(4-ethyl-2,3-dioxopiperazin-1-yl)carbonyl]amino}acetyl]amino}-2-(5-{[(1-methyl-1,2,3,4-tetraazol-5-yl)sulfanyl]methyl}-4-oxo-2H,3H,4H-1,3-thiazin-2-yl)acetic acid