Synthesis of N -substituted phthalimides via Pd-catalyzed [4+1] cycloaddition reaction.

A novel Pd-catalyzed assembly of N -substituted phthalimides by merging of [4+1] cycloaddition and difluorocarbene transfer carbonylation from 2-iodo- N -phenylbenzamides and difluorocarbene precursors is disclosed. Difluorocarbene acts as a carbonyl source and simultaneously forms one C-C bond, one C-N bond and one CO bond to produce N -substituted phthalimides in high yields.