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 5-tert-butyl-N-methyl-2-(1-phenylethyl)-6,7,8,9-tetrahydro-5H-pyrimido[4,5-d]azepin-4-amine .
user
C21H30N4
assistant