You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Provide the molecular formula for the IUPAC named substance 2-(7-hex-4-enoyloxy-8,8a-dimethyl-3-oxo-1,2,7,8-tetrahydronaphthalen-2-yl)prop-2-enoic acid .
user
C21H26O5
assistant