(2S,3R)-2-((1S,2R)-1-carboxy-2-(pivaloyloxy)propyl)-4-((1-(4,5-dihydrothiazol-2-yl)azetidin-3-yl)thio)-4-(hydroxymethyl)-3-methyl-3,4-dihydro-2H-pyrrole-5-carboxylic acid