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system
Name the molecular formula for the molecule established as (E)-3-[1-[(4-nitrophenyl)sulfonylamino]-2,3,3a,8b-tetrahydro-1H-cyclopenta[b][1]benzofuran-5-yl]prop-2-enoic acid using the IUPAC nomenclature.
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C20H18N2O7S
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