You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Convert the IUPAC name of a molecule methyl 4-chloro-5-[9-[(2-methylpropan-2-yl)oxycarbonylamino]-5-oxo-5lambda4-thia-8-azaspiro[3.5]non-8-en-7-yl]thiophene-2-carboxylate into molecular formula.
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C18H23ClN2O5S2
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