Ligand-Controlled\nSelective Synthesis of Indoles and\nBenzofurans from Secondary Anilines

A ligand-controlled method for the selective synthesis\nof indoles\nand benzofurans from secondary anilines has been discovered. A six-ring\npalladacycle intermediate may be involved in this process by olefins\nas a transient directing mediator to give indoles. The indole/benzofuran\nratio can be easily tuned by the MPAA ligand. Various substituted\nsecondary anilines were well-tolerated, affording the corresponding\nproducts in moderate to good yields. Indole-derived drugs such as\nJWH-081, BB-22, and ML-098 could be obtained using our new method\nto achieve their precursors. Preliminary mechanistic studies indicated\nthat BQ is the key factor in avoiding the β-H elimination of\ninsertion species.