You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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For the molecule named (2S,3R)-2-[(2-benzyl-5,6,7,8-tetrahydro-[1]benzothiolo[2,3-d]pyrimidin-4-yl)amino]-3-hydroxybutanoic acid by IUPAC nomenclature, provide its molecular formula.
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C21H23N3O3S
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