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system
Name the molecular formula for the molecule established as (1R,9S)-6-bromo-3-hydroxy-4,12-dimethoxy-17-azatetracyclo[7.5.3.01,10.02,7]heptadeca-2,4,6,11-tetraen-13-one using the IUPAC nomenclature.
user
C18H20BrNO4
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