An efficient catalytic method for the Friedlنnder annulation mediated by peptide coupling agent propylphosphonic anhydride (T3P®)

We have demonstrated the utilization of T3P, a mild and low toxic peptide coupling agent, as a promoter and water scavenger in the Friedlنnder annulation, and thus introduced a highly efficient catalytic process to access carbocyclic and heterocyclic fused quinolines under microwave irradiation or a conventional heating technique. The reaction conditions are sufficiently mild to tolerate the acid and base sensitive functional groups that can serve as levers for further extension of the quinoline products.