You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named [(2R)-1-oxo-1-(7H-purin-6-ylamino)propan-2-yl] 2-[(4-methyl-1,3-thiazol-2-yl)sulfanylmethyl]benzoate by IUPAC nomenclature, provide its molecular formula.
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C20H18N6O3S2
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