Synthesis of 14C‐ and 3H‐labeled CI‐911 (dihydro‐1H‐pyrrolizine‐3, 5 (2H, 6H)‐dione)

CI‐911 [dihydro‐1H‐pyrrolizine‐3,5(2H, 6H)‐dione] (1), a new cognition activating agent, was radiolabeled with 14C and 3H. The 14C‐labeled synthesis was accomplished using nitromethane‐14C as the starting material to result in an overall radiochemical yield of 9.2%. The 3H‐labeled CI‐911 was synthesized with a specific activity of 28.1 Ci/mmol by catalytic tritium reduction of 3‐(5‐oxo‐2‐pyrrolidinyl)‐2‐propenoic acid, phenylmethyl ester, followed by cyclization upon heating with acetic anhydride.