Q: What is the definition of this compound's USAN stem?
 The Compound has the SMILES C[C@@H]1CN(Cc2ncccn2)C[C@H]1c1cn2c(C3CCOCC3)ncc2c(=O)[nH]1.
Answer: phosphodiesterase type 9 (PDE9) inhibitors; vinca alkaloids
{#Question|Q!}: {quest#}
{#Constraint:|Description:|!} The {#Molecule|Compound|Chemical!} {#has the|can be represented with the!} {SMILES__description} {SMILES#}.
{#Answer|Result|Answer!}: {answ#}
C[C@@H]1CN(Cc2ncccn2)C[C@H]1c1cn2c(C3CCOCC3)ncc2c(=O)[nH]1
C[C@@H]1CN(Cc2ncccn2)C[C@H]1c1cn2c(C3CCOCC3)ncc2c(=O)[nH]1
6-[(3S,4S)-4-methyl-1-(pyrimidin-2-ylmethyl)pyrrolidin-3-yl]-3-(oxan-4-yl)-7H-imidazo[1,5-a]pyrazin-8-one
What is the definition of this compound's USAN stem?