A comparison of the incorporation of 123I and 18F into 1-[1-(3-hydroxyphenyl) cyclohexyl]-4-(methanesulfonyloxy)piperidine by nucleophilic displacement with 123I− and 18F−
✍ Scribed by Xiao-Shu He; Dale O. Kiesewetter; Kan Sam Lee; Mariena V. Mattson; D. R. Weinberger; Brian R. de Costa
- Publisher
- John Wiley and Sons
- Year
- 1993
- Tongue
- French
- Weight
- 474 KB
- Volume
- 33
- Category
- Article
- ISSN
- 0022-2135
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
Unlabelled and labelled 4‐fluoro‐ and 4‐iodo‐1‐[1‐(3‐hydroxyphenyl)cyclohexyl]piperidines (3 and 4, respectively), derivatives of phencyclidine, were synthesized in 3‐steps via nucleophilic displacement reaction of 1‐[1‐(3‐hydroxyphenyl) cyclohexyl]‐4‐(methanesulfonyloxy)piperidine (8). The displacement reaction with 3 molar equivalents of Bu~4~N^+^I^−^ gave 58% of 4 with no detectable methanesulfonate elimination. Reaction of a large excess of 8 with Na^123^I^−^ under similar conditions gave up to 40% yield of [^123^I]8. In contrast reaction of 8 with 3 molar equivalents of unlabelled Bu~4~N^+^F^−^ in refluxing acetonitrile yielded only 3.1% of 3 and 97% of elimination product. Similarly, reaction of a large excess of 8 with Bu~4~N^+18^F^−^ at 80 °C in acetonitrile failed to yield detectable quantities of [^18^F]3. However, low (0‐4%) yields of [^18^F]3 were obtained using ^18^F^−^ in the presence of varying proportions of inorganic base and Krytofix in acetonitrile.