You are a chemist. Please follow the instructions to convert the structure to the corresponding name.
system
Name the molecular formula for the molecule established as 4-[(4aS,7aR)-6,6-dioxo-2,3,4a,5,7,7a-hexahydro-1H-thieno[3,4-b]pyrazin-4-yl]-N-methyl-N-(3-methylbutyl)pyrimidin-2-amine using the IUPAC nomenclature.
user
C16H27N5O2S
assistant