(2R)-2-[(4S)-9-cyano-4-methoxy-1-[(7aR,7S)-7-methoxy-3-{[(1-methyl-1,2,3,4-tetraazol-5-yl)sulfanyl]methyl}-6-oxo-7-{[(thioformyl)carbonyl]amino}-2,6,7,7a-tetrahydroazeto[2,1-b][1,3]thiazin-4-yl]-1,3,6-trioxo-5-aza-2-oxa-8-thianon-4-yl]-5-{[(1-methyl-1,2,3,4-tetraazol-5-yl)sulfanyl]methyl}-2H,3H,6H-1,3-thiazine-4-carboxylic acid