Cobalt(III)‐Catalyzed Redox‐Neutral Synthesis of Unprotected Indoles Featuring an N−N Bond Cleavage

Abstract

A redox-neutral cobalt(III)-catalyzed synthetic approach for the direct synthesis of unprotected indoles showcasing an N-N bond cleavage is reported. The herein newly introduced Boc-protected hydrazines establish a beneficial addition to the limited portfolio of oxidizing directing groups for cobalt(III) catalysis. Moreover, the developed catalytic methodology tolerates a good variety of functional groups.

Mild C−H/C−C Activation by Z‐Selective Cobalt Catalysis

“…[8] Therecent years have witnessed increasing interest in the use of naturally abundant 3d transition metal catalysts for CÀH functionalizations. [9] Particularly,c obalt(III) complexes have emerged as versatile tools, [10] with key contributions by Matsunaga/Kanai, [11] Ellman, [12] Chang, [13] Glorius, [14] Shi, [15] Jiao, [16] and Ackermann, [17] among others. [18] As part of our research on base-metal-catalyzed C À Hactivation, [19] we have now developed the first cobalt-catalyzed CÀH/CÀCfunctionalization.…”

Theoretical prediction on the synthesis of 2,3‐dihydropyridines through Co(III)‐catalysed reaction of unsaturated oximes with alkenes

“…So far, the majority of developed CH activation methods employ catalysts based on noble transition metals such as Ru, Rh, Pd, or Ir . More recently, earth‐abundant and cost‐efficient first‐row transition metals, especially Co, have emerged as attractive alternatives to the noble metals . Among them, the Cp*Co(III) catalysts not only emulate the known catalytic capabilities of Cp*Rh(III) efficiently, but also exhibit other unique reactivities .…”

Cp*CoIII‐Catalyzed Bis‐isoquinolone Synthesis by C−H Annulation of Arylamide with 1,3‐Diyne

“…Lee [5c] and Satoh-Miura [5d] independently reported intra-and intermoleculara nnulations using diynes as coupling partners.G lorius and co-workers reported the first redox bis-annulation of benzamidea nd oxime using diyne as an alkynep artner through Rh III -catalyzed CÀHb ond activation. In this regard,t he Cp*Co III [7,8] catalysti se merging as ap romising candidate after the seminalc ontributionb yM atsunaga-Kanaia nd co-workers. In this regard,t he Cp*Co III [7,8] catalysti se merging as ap romising candidate after the seminalc ontributionb yM atsunaga-Kanaia nd co-workers.…”

“…However,asignificant drop in the yield waso bservedw hen cobalt(III) iodideo rc hloride dimer was employed in place of the monomer (entries [8][9]. Among different solvents screened, best result was obtained for 2,2,2-trifluoroethanol as the solvent for alkyne-tethered isoquinolonea sasingle regioisomer (entries 1-5).…”