You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
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Under IUPAC nomenclature, a molecule named [(2S)-1-methoxypropan-2-yl] (2S)-2-[3-(azepan-1-yl)quinoxalin-2-yl]-2-cyanoacetate is given. What is its corresponding molecular formula?
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C21H26N4O3
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