[(2,2-dimethylpropanoyl)oxy]methyl (7aR,7R)-7-{[(2Z)-2-[2-({[(7aR,7R)-7-{[(2Z)-2-(2-amino-1,3-thiazol-4-yl)-1-oxopent-2-enyl]amino}-3-[(carbamoyloxidanyl)methyl]-6-oxo-2,6,7,7a-tetrahydroazeto[2,1-b][1,3]thiazin-4-yl]carbonyl}amino)-1,3-thiazol-4-yl]-1-oxopent-2-enyl]amino}-3-[(carbamoyloxidanyl)methyl]-6-oxo-2,6,7,7a-tetrahydroazeto[2,1-b][1,3]thiazine-4-carboxylate