You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Please write the molecular formula of the molecule 7-[[4-[3-(4-chlorophenoxy)propanoyl]piperazin-1-yl]methyl]-[1,3]thiazolo[3,2-a]pyrimidin-5-one .
user
C20H21ClN4O3S
assistant