(S)-6-[(4-Chlorophenyl)(1H-1,2,4-triazol-1-yl)methyl]-1-[11C]methyl-1H-benzotriazole

Aromatase is an enzyme complex of the cytochrome P450 superfamily (1). It is composed of P450 and a flavoprotein called NADPH-P450 reductase. Its main function is to aromatize androgens to estrogens. Aromatase is present in many tissues, including granulosa cells of the ovary, brain, fat, placenta, blood vessels, skin, bone, and endometrium. Aromatase is overexpressed in tissue of endometriosis, uterine fibroids, breast cancer, and endometrial cancer (2-6). (S)-6-[(4-Chlorophenyl)(1H-1,2,4-triazol-1-yl)methyl]-1-methyl-1H-benzotriazole (vorozole) is an aromatase inhibitor with a inhibition constant (Ki) value of 1 nM. Lidstrom et al. (7) prepared [11C]vorozole by N-methylation of (S)-6-[(4-chlorophenyl)(1H-1,2,4-triazol-1-yl)methyl]-1H-benzotriazole (nor-vorozole) to use as a positron emission tomography (PET) radioligand to study aromatase activity.