Syntheses of AZ12320927 labeled with H‐3, C‐14, and H‐2

In support of a program to develop a treatment for depression, three isotopically labeled forms of the 5‐HT1B antagonist AZ12320927 were synthesized. A tritium labeled version was synthesized for autoradiography using Ir‐catalyzed hydrogen–tritium exchange. A C‐14 labeled version was prepared for use in metabolism studies in four‐steps from [u‐14C]p‐nitrophenol. A stable isotope labeled version was synthesized for use as an internal standard for LC/MS/MS quantitation in two steps from chromenone 1.