Studies on the formation of C-N bond using hypervalent iodine and transition metal catalyst

Abstract

A new synthetic approach toward intermolecular oxidative C-N bond formation of arenes has been developed under transition-metal-free conditions. Complete control of chemoselectivity between aryl sp2 and benzylic sp3 C-H bond imidation was achieved by the choice of nitrogen sources, representatively being phthalimide and dibenzenesulfonimide, respectively. Detailed mechanistic pathway was confirmed by KIE and competition test with arenes bearing different electronic environment. In addition, iodine-nitrogen complex regarded as reaction intermediate was detected by ESI-MS method. A metal-free procedure that is simple to operate and convenient to handle was developed for the facile intramolecular oxidative diamination of olefins using an iodobenzene diacetate oxidant and a halide additive to furnish bisindolines at room temperature. The present reaction is featured by mild conditions, a broad substrate scope, and excellent functional group tolerance. The same protocol was successfully extended to the urea moiety to afford bicyclic products and aminohydroxylation of the stilbene derivative bearing phenol functional group. We develop the rhodium-catalyzed diamination and unsymmetric functionalization of the arenes with purine directing group via hydrogen bonding interaction. Many examples of the arene functionalization were reported since C-H activation protocol has been developed, however, functionalization of arene via hydrogen bonding was remained with unexplored field. The exact role of the nitrogen in purine directing group was confirmed by designed experiment and the scope of the present route to afford diaminated arene products turned out to be quite general. Moreover, different amine sources and electrophile source were reactive to provide unsymmetric functionalized arene.