Rhodium‐Catalyzed Hydrogen‐Releasing ortho‐Alkenylation of 7‐Azaindoles

Abstract

An efficient rhodium-catalyzed dehydrogenative Heck-type reaction between N-aryl-substituted 7-azaindoles and various alkenes through a H -releasing process without the need of any oxidizing agent was developed. The novel methodology broadens the scope of metal-catalyzed hydrogen-releasing reactions to include rhodium catalysis.

A comprehensive overview of directing groups applied in metal-catalysed C–H functionalisation chemistry

“…), which acts as a hydrogen acceptor. 966 Another version of this transformation (not shown in scheme), was reported by Miura and Satoh. Despite the use of superstoichiometric Ag as oxidant and DME as solvent, this method allows fast reactions (3–6 h) under mild conditions (40–90 °C), giving generally good to excellent results.…”

“…A number of functionalisations have been reported using procedures similar to those for other DGs, exclusively under Rh (in one case Ir) catalysis. Among the alkylation and olefination with α,β-unsaturated moieties ( Scheme 157A–C ), 964 – 966 an interesting cross-dehydrogenative olefination procedure which does not require the presence of a stoichiometric oxidant (as is usually the case), was reported by Dong ( Scheme 157C ). 966 In this reaction the Rh( iii ) hydride intermediate formed at the final stage of the olefination process reacts with the acid, releasing H 2 .…”

Chemo-selective couplings of anilines and acroleins/enones under substrate control and condition control

“…Our initial Rh(III)-catalyzed coupling of N-(2-pyridyl)aniline with acrolein using a stoichiometric amount of Cu(II) oxidant in EtOH afforded the desired dihydroquinolone (4af) in 92% yield. Of note, during the optimization of this system, a yield of 25% was also realized even in the absence of any external oxidant, which might indicate either hydrogen-releasing coupling or TH with acrolein being a sacrificial hydrogen acceptor (vida infra) [64][65][66][67]. To avoid using a stoichiometric amount of copper(II), different solvents and acid additives were then evaluated.…”

Regioselective C-H Functionalization of the Six-Membered Ring of the 6,5-Fused Heterocyclic Systems: An Overview

“…In various reported studies, the regioselectivities of C-H and C-H/C-H activations were controlled by DG such as monodentate amides [13,14], carboxylic acids [15], ketones [15][16][17], nitriles [18,19], aldehydes [15,20], phenols [21,22], esters [15,16,23], amides [15,16], N-methoxybenzamide [24], ureas [25,26], imines [27,28], hydrazines [29,30] and hydrazones [31], bidentate ligands [6], carbamates [32], sulfoxides [33], sulfonamides [34,35], sulfoximines [36], phosphine oxides [37,38], sulfides [39], thioamides [40] as well as some heterocycles such as purines [41], pyrimidines [42], pyrazoles [43,44], oxazolines [44], azoles [45], benzothiazoles [46], oxadiazoles [47], benzoxazoles [48,49] and 7-azaindole [50]. In some ca...…”