Carbon-14 Labeling Synthesis of RORγt Inhibitor JNJ-61803534

Carbon-14 labeling synthesis of RORγt inhibitor JNJ-61803534 (1) was accomplished in four steps with the C14 label located at the thiazole-2-carboxamide carbon. The synthesis featured a highly efficient conversion of nitrile [¹⁴C]-12 to ester [¹⁴C]-17 under mild conditions via an imidate intermediate, overcoming the unsuccessful direct hydrolysis of nitrile 12 under either acidic or basic conditions. Since carbon-14 labeling via [¹⁴C]-nitrile installation and subsequent conversion to [¹⁴C]-carboxylic acid derivatives is a common labeling strategy, an efficient conversion of a nitrile to an ester under mild conditions could be of use for the future C14 labeling syntheses.