(3R,4R)-1-[(1S)-carboxy-2-(methylsulfinyl)ethyl]-3-[(5S)-5-amino-5-carboxypentanamido]-4-sulfanylazetidin-2-one
(3r,4r)-1-[(1s)-carboxy-2-(methylsulfinyl)ethyl]-3-[(5s)-5-amino-5-carboxypentanamido]-4-sulfanylazetidin-2-one