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 2-[(8R)-7-[2-(3,4-dihydro-2H-chromen-6-yl)acetyl]-8-methyl-6,8-dihydro-5H-imidazo[1,2-a]pyrazin-2-yl]-N,N-dimethylacetamide .
user
C22H28N4O3
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