Tetrafluoroindole (5), a precursor for potential biologically-active compounds, was prepared previously in a four-step synthesis from C6F6. However, catalytic reduction of pentafluorophenylacetonitrile (2) to 2-pentafluorophenylethyl amine (3) is accompanied by a significant amount of a secondary amine, which, like 3, undergoes cyclization to an indoline and subsequent dehydrogenation to a new indole 8. The side-reaction in the reduction of ...
