SummaryA method for scavenging excess amines in sulfur-35-labeled radioligand preparations using fluorous scavengers has been developed in an effort to simplify the purification. This fluorous scavenging has been shown to be effective at removing excess amines from several [35 S]sulfonylation mixtures. In many cases this results in one less semipreparative HPLC purification, and thus in higher radiochemical yield and time savings. Fluorous scavenging was compared to the use of a solid-phase resin (PSisocyanate) and determined to be approximately equal with respect to recovery of radioactive product. However, the fluorous scavengers were shown to be more effective than solid-phase resin for removing basic amine components.

Here we report an efficient synthesis of 14C‐labeled 6‐[2‐(dimethylamino)ethyl]‐14‐(1‐ethylpropyl)‐5,6,7,8‐tetrahydroindolo‐[2,1‐α][2,5]benzodiazocine‐11‐carboxylic acid (1) using the Curtius rearrangement as a key step. The synthesis was initiated by converting the unlabeled aryl carboxylic acid to an aryl amine via Curtius rearrangement reaction. The resulting aryl amine was then converted to an aryl iodide which was coupled with zinc [14C]cyanide to form an aryl [14C]nitrile. Subsequent hydrolysis yielded the 14C‐labeled carboxylic acid [14C]‐1. This overall process represents a mild and potentially general approach for conversion of unlabeled carboxylic acids to isotopically labeled carboxylic acids. Copyright © 2010 John Wiley & Sons, Ltd.