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 1-(4-imidazo[1,2-a]pyrazin-3-yloxyphenyl)-2-[5-methyl-4-(trifluoromethyl)pyridin-2-yl]ethanone into its molecular formula.
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C21H15F3N4O2
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