The nucleophilic iron complex Bu4N[Fe(CO)3(NO)] (TBA[Fe]) catalyzes the direct intramolecular amination of unactivated C(sp3)−H bonds in alkylaryl azides, which results in the formation of substituted indoline and tetrahydroquinoline derivatives.

Whereas the direct catalytic amination of C(sp2)−H bonds has evolved as a powerful method in organic synthesis, the corresponding direct catalytic amination of unactivated C(sp3)−H bonds might be considered as underdeveloped. To render this thermodynamically unfavorable pathway possible, two distinct strategies have evolved for the catalytic amination of C(sp3)−H bonds, namely the use of strong oxidants to generate nitrenoid species and the “oxidant-free” method, which relies on the use of azides as nitrogen donor reagents.1 The groups of DuBois,2 Müller,3 Lebel,4 and, most recently, White5 have developed sophisticated amination methods that involve the use of additional oxidants in the presence of Rh-, Ir-, Cu-, or even Mn-based catalysts. Over the past years, the groups of Driver,6 Zhang,7 DeBruin,8 and MacBeth9 have reported interesting systems for “oxidant-free” C(sp3)−H aminations of unactivated C−H bonds, using either a Rh, Ir, or Co catalyst. Despite the significant progress in the field of Fe catalysis, it was only recently that Betley10 and co-workers published landmark reports on a non-oxidative Fe(+1)-catalyzed intramolecular amination of C(sp3)−H bonds using alkyl azides as N donors [Eq. (1), Figure 1].1c, 8, 11 Mechanistic studies indicated that the process follows a stepwise radical mechanism.