Synthesis of indolines, indoles, and benzopyrrolizidinones from simple aryl azides.

A simple approach to prepare indolines and benzopyrrolizidinones from ortho-azidoallylbenzenes via a tandem radical addition/cyclization is described. The use of triethylborane to initiate and sustain the process provides the best results. Indolines are easily converted into the corresponding indoles by oxidation with manganese dioxide.