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 [ 14 C]‐ 12 to ester [ 14 C]‐ 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 [ 14 C]‐nitrile installation and subsequent conversion to [ 14 C]‐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.