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 1-[4-[[(2S,4aS,6R,7R,8S,8aR)-2-(3-bromophenyl)-7,8-dihydroxy-4,4a,6,7,8,8a-hexahydropyrano[3,2-d][1,3]dioxin-6-yl]oxy]phenyl]ethanone into molecular formula.
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C21H21BrO7
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