You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Can you give the molecular formula of the molecule N-ethyl-2-[(2R,4S)-2-methyl-1-prop-2-enoylpiperidin-4-yl]oxy-5H-pyrrolo[2,3-b]pyrazine-7-carboxamide ?
user
C18H23N5O3
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