Iron-Catalyzed Functionization Of Indoles

Indole, as a basic backbone, is frequently found in many natural bioactive products, marketed drugs, functional materials, and agrochemicals. Since its discovery, enormous efforts have been devoted to the development of ever more efficient synthetic protocols for the preparation and direct functionalization of this heteroaromatic compound. In recent years, the development of new environmentally benign catalysts with enhanced reactivity has aroused much attention in the studies of indole functionalization. Iron as inexpensive and environmentally benign catalysts has been increasingly explored in organic transformations and significant advances have been made in iron catalyzed indole reaction.This dissertation mainly focused on the studies of transition metal iron-catalyzed indole functionalization reaction, which include:1. FeCl3-promoted alkylation of indoles by enamidesWe report a highly efficient method for the addition of indoles to enamides in the presence of iron catalyst under mild reaction conditions. This facile catalytic system was also applicable to indolizines. The simple catalytic system worked well with a broad range of indoles and allowed the facile synthesis of alkylated indoles as well as symmetric and unsymmetric bis-indolylmethanes.2. Iron-catalyzed oxidative homo-coupling of indoles via C-H cleavageWe have demonstrated a new method for the direct formation of 3, 3'-biindolyls by an iron-catalyzed dimerization of 2-arylindole using molecular oxygen as the only oxidant. The reaction proceeded well for a range of electron-rich as well as electron-poor 2-arylindoles and is tolerant of functional group such as chloride, bromine and iodine. The reaction provides a facile and efficient route to the preparation of 3,3'-biindolyls.