Access to Cyclopentenone via Pd(0)-Catalyzed Reductive Cyclization of (Z)-5-Iodo-4-pentenenitrile

A ligand-free Pd(0)-catalyzed cyclization of (Z)-5-iodo-4-pentenenitrile has been realized with the help of HCO₂H reductant, which is followed by imine hydrolysis to afford cyclopentenone derivatives in moderate to good yields. Control experiments clearly points out that the proton originally came from HCO₂H plays a crucial role on protonation of the resultant imido-Pd²⁺ intermediate. This protocol features mild condition, operational simplicity, as well as wide functional group tolerance.