The Hemetsberger-Knittel Synthesis of Substituted 5-, 6-, and 7-Azaindoles

A series of substituted 5-, 6-, and 7-azaindoles were prepared via the Hemetsberger-Knittel reaction. In general, better yields were obtained at higher temperatures and shorter reaction times than required for the formation of the analogous indoles, and in some cases, only decomposition occurred below a minimum temperature. The resulting templates offer up to five sites for subsequent functionalization to allow a wide range of chemical diversity.