You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Translate the chemical IUPAC name methyl 2-[(1R,3S,4aS,9aR)-6-(cyclobutanecarbonylamino)-1-(hydroxymethyl)-3,4,4a,9a-tetrahydro-1H-pyrano[3,4-b][1]benzofuran-3-yl]acetate into its molecular formula.
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C20H25NO6
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