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 (4aS,9bR)-6-butylsulfanyl-8-(2,4-dichlorophenyl)-1,2,3,4,4a,9b-hexahydro-[1]benzofuro[3,2-c]pyridine .
user
C21H23Cl2NOS
assistant