Aztreonam t-Butyl Ester 

Chemical Name: (Z)-2-[[[(2-Amino-4-thiazolyl)[[(2S,3S)-2-methyl-4-oxo-1-sulfo-3-azetidinyl] carbamoyl]methylene]amino]oxy]-2-methylpropionic acid t-butyl ester 

Smile: CC(C)(O/N=C(C1=CSC(N)=N1)\C(N[C@H]2[C@H](C)N(S(=O)(O)=O)C2=O)=O)C(OC(C)(C)C)=O