Iron-Catalyzed Direct Suzuki–Miyaura Reaction: Theoretical and Experimental Studies on the Mechanism and the Regioselectivity

Abstract

The mechanism of the Suzuki−Miyaura cross-coupling reaction between pyridine and phenylboronic acid catalyzed by the complex of iron salt combined with macrocyclic polyamine (iron−MCPA) was investigated theoretically and experimentally. It was found that the overall reaction includes three steps: C−H activation, transmetalation, and reductive elimination. The results indicate that the rate-determining step is the transmetalation step. The C−H activation of a different position on pyridine is the origin of the regioselectivity. The transmetalation step is the regio-determining step. Both the C−H activation and the transmetalation steps favor the regioselective formation of the ortho product. The oxoiron complex is predicted to be the active species theoretically and is confirmed by experiments. The calculations correctly reproduce the major product, 2-phenylpyridine, which is consistent with the experimental observation.

Modification of palladium–copper thin film by reduced graphene oxide or platinum as catalyst for Suzuki–Miyaura reactions

“…The results show that aryl iodide and bromide are more suitable substrates for biaryl synthesis. The catalytic cycle of SMC reactions includes three steps: (1) oxidative addition, (2) transmetallation and (3) reductive elimination . The oxidative addition of palladium into a carbon–halogen (C─X) bond occurs in the order I > Br > > Cl > > F, based mainly on the strength of the C─X bond .…”

Iron Catalysis in Organic Synthesis

“…A reasonable mechanistic pathway and the course of the regioselectivity have been supported by DFT calculations. 481 An air-induced formation of an oxoiron complex is proposed to be followed by a directed metalation of the heteroarene (CÀH bond activation), a subsequent transmetalation, and finally a reductive elimination.…”

Recent Developments in the Immobilization of Palladium Complexes on Renewable Polysaccharides for Suzuki–Miyaura Cross-Coupling of Halobenzenes and Phenylboronic Acids

“…Since its introduction in 1979 by Akira Suzuki et al [7], the Suzuki cross-coupling of halobenzenes and organoborons ( Figure 1) (which earned Akira Suzuki the Nobel Prize in 2010), was successfully performed with numerous homogeneous and heterogeneous palladium-based catalysts, with the addition of a base as co-catalyst [4][5][6][7][8][9][10][11][12]. Although palladium was the main target metal of many research efforts and various industrial cross-coupling protocols, other metals like nickel [13][14][15], iron [16,17] rhodium [18][19][20], and copper [21], were also found to be active in Suzuki cross-coupling, and their applications in that context were thus investigated. In the last two decades, many homogeneous complexes and heterogeneous catalysts were synthesized and tested for their suitability in the Suzuki reaction.…”