Iridium-catalyzed ortho-C–H borylation of aromatic aldimines derived from pentafluoroaniline with bis(pinacolate)diboron

Abstract

The development of an Ir-catalyzed ortho-C–H borylation of aromatic aldimines derived from pentafluoroaniline is reported.

Accessing Ambiphilic Phosphine Boronates through C−H Borylation by an Unforeseen Cationic Iridium Complex

“…Early work in the area of metal‐catalyzed C−H borylation reactions utilized catalysts that were sterically‐controlled, avoiding ortho C−H bonds in arenes and favoring primary C−H bonds for alkanes . Starting in 2008, new systems were developed that utilized directing groups to achieve alternative selectivity patterns ( ortho ‐ or meta ‐directed) . The approaches used to achieve directed C−H borylation are diverse, but, the key to achieving the desired directing effect has been to modify the catalyst in a way that the directing interaction does not form a coordinatively saturated 18‐electron complex, which then has no open site for activation of the C−H bond.…”

Accessing Ambiphilic Phosphine Boronates through C−H Borylation by an Unforeseen Cationic Iridium Complex

“…Early work in the area of metal‐catalyzed C−H borylation reactions utilized catalysts that were sterically‐controlled, avoiding ortho C−H bonds in arenes and favoring primary C−H bonds for alkanes . Starting in 2008, new systems were developed that utilized directing groups to achieve alternative selectivity patterns ( ortho ‐ or meta ‐directed) . The approaches used to achieve directed C−H borylation are diverse, but, the key to achieving the desired directing effect has been to modify the catalyst in a way that the directing interaction does not form a coordinatively saturated 18‐electron complex, which then has no open site for activation of the C−H bond.…”

Regioselective C–H Borylation of Heteroaromatic Aldimines with Iridium Complexes

“…The borylation of the pentafluoroaniline-derived heteroaromatic aldimine 1a was initially examined under the optimum conditions that we previously established for the borylation of aromatic aldimines (Table 1). 12,13 Unfortunately, the reaction of aldimine 1a with borane 2 (1.0 equiv) in the presence of [Ir(OMe)(cod)] 2 (1.5 mol%), the ligand P(C 6 F 5 ) 3 (6.0 mol%), and 2-norbornene (1.0 equiv) in mesitylene at 120 °C afforded the corresponding product 3a in only 5% yield after 24 hours (Table 1, entry 1). We then screened other possible ligands (entries 2-7), and we discovered that no reaction occurred when Ph 3 As was used as the ligand (entry 2).…”