Carbon-14 labeling of a trifluoromethoxy group: synthesis of a substance P antagonist

Synthesis of a carbon‐14 labeled trifluoromethoxy group has been accomplished using the stepwise oxidative fluorination–desulfurization of a readily prepared [14C]xanthate (5). This novel labeling procedure allowed a rapid synthesis of substance P antagonist candidate 1 that avoided potentially more complex ring‐labeling procedures. Similar procedures have been used to prepare C‐14 labeled trifluoromethyl and trifluoromethylamine groups. Copyright © 2001 John Wiley & Sons, Ltd.