You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
What is the molecular formula of the molecule (1S,9S)-13-(2-ethoxy-2-oxoethylidene)-5-methoxy-11-methyl-6-azatricyclo[7.3.1.02,7]trideca-2(7),3,5,10-tetraene-1-carboxylic acid ?
user
C19H21NO5
assistant