Carbonic acid (1R)-1-[(2R,3S)-2-[[(ethylthio)thioxomethyl]thio]-4-oxo-3-azetidinyl]ethyl 2,2,2-trichloroethyl ester

2,2,2-trichloroethyl [2R-[2alpha,3beta(R*)]]-1-[2-[[(ethylthio)thioxomethyl]thio]-4-oxoazetidin-3-yl]ethyl carbonate