Synthesis of 1,1′ [ 11 C]‐methylene‐di‐(2‐naphthol) ([ 11 C]ST1859) for PET studies in humans

1,1′‐Methylene‐di‐(2‐naphthol) (ST1859), a candidate drug for the treatment of Alzheimer's disease, was radiolabelled with carbon‐11 with the aim to perform PET microdosing studies in humans. The radiosynthesis was automated in a commercial synthesis module (Nuclear Interface PET tracer synthesizer) and proceeded via reaction of [ 11 C]formaldehyde with 2‐naphthol. [ 11 C]formaldehyde was prepared by catalytic dehydrogenation of [ 11 C]methanol (conversion yield: 48±11% ( n = 19)) employing a recently developed silver‐containing ceramic catalyst. Starting from 69±3 GBq of [ 11 C]carbon dioxide ( n = 19), 4±1 GBq of [ 11 C]ST1859 (decay‐corrected to the end of bombardment), readily formulated for intravenous administration, could be obtained in an average synthesis time of 38 min. The specific radioactivity of [ 11 C]ST1859 at the end of synthesis exceeded 32 GBq/µmol. Copyright © 2005 John Wiley & Sons, Ltd.