Trans-Selective Carboxylative Cyclization of 1,6-Dienes Using the CO2 Radical Anion

The reactivity of the carbon dioxide radical anion (CO2•−) toward alkenes has garnered remarkable attention owing to its potential to synthesize valuable organic compounds. Herein, we report the reactions between CO2•− and 1,6-dienes, yielding 5-membered lactam derivatives via highly trans-selective 5-exo-trig cyclization. Both carboxylative cyclization and hydrocyclization occur with up to 74% combined yield. Computational studies show that the transition state during cyclization favors the trans-configuration over cis. This work offers new insights into the synthesis of N-heterocycles.