(4R,5S,6S)-(Pivaloyloxy)methyl 3-((1-(4,5-dihydrothiazol-2-yl)azetidin-3-yl)thio)-6-((R)-1-hydroxyethyl)-4-methyl-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate

for the following products (1R,5S,6S)-6-[1(R)-hydroxyethyl]-1-methyl-2-[1-(2-thiazolin-2-yl)azetidin-3-ylsulfanyl]-1-carba-2-penem-3-carboxylic acid pivaloyloxymethyl ester | Tebipenem pivoxil and (4R,5S,6S)-(Pivaloyloxy)methyl 3-((1-(4,5-dihydrothiazol-2-yl)azetidin-3-yl)thio)-6-((R)-1-hydroxyethyl)-4-methyl-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate