You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule (6R,7R)-7-[[(2E)-2-[2-[(2-chloroacetyl)amino]-1,3-thiazol-4-yl]-2-methoxyiminoacetyl]amino]-8-oxo-3-(3-oxobutanoyloxymethyl)-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid .
user
C20H20ClN5O9S2
assistant