You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Translate the chemical IUPAC name methyl 1-[2-[5-(2-aminoethylsulfanyl)-1,3-thiazol-2-yl]acetyl]-5-chlorospiro[2H-indole-3,3'-pyrrolidine]-1'-carboxylate into its molecular formula.
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C20H23ClN4O3S2
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