Synthesis of binuclear iridium(III) and rhodium(III) complexes bearing methylnaphthalene-linked N-heterocyclic carbenes, and application to intramolecular hydroamination

Ogata, Kenichi; Nagaya, Toshinori; Fukuzawa, Shin‐ichi

doi:10.1016/j.jorganchem.2010.04.006

Cited by 26 publications

(8 citation statements)

References 68 publications

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“…where the active catalysts were also synthesized by addition of a Ag salt to abstract one of the chloride ligands. 17 These complexes were moderately active for the hydroamination of 2-(2-phenylethynyl)aniline, achieving less than 73% conversion of the substrate after 24 h in refluxing acetonitrile with 10 mol % metal loading, where the best catalyst we report here (16a) achieves 90% conversion in 1.5 h, with 5% loading. Consistent with our results, a higher catalyst activity was observed by Ogata et al for their Ir compounds compared to their Rh compounds, with the highest activity obtained for the catalyst containing the least sterically bulky NHC ligand.…”

Section: ■ Results and Discussionmentioning

confidence: 76%

Iridium(III) Cp* Complexes for the Efficient Hydroamination of Internal Alkynes

et al. 2012

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A series of iridium(III) and rhodium(III) 1,2,3,4,5-pentamethylcyclopentadienyl (Cp*) complexes of the type [M(Cp*)(LL)Cl]BPh 4 were synthesized, where LL is a chelating diimine or mixed pyrazolyl-phosphine or pyrazolyl-N-heterocyclic carbene donor ligand. The majority of these complexes were characterized by X-ray crystallography, allowing for a detailed comparison of their structural properties. These complexes were shown to yield active hydroamination catalysts upon in situ abstraction of the chloride coligand using AgBF 4 . The activity of these catalysts for the intramolecular hydroamination of alkyne-amines to yield indolyl and pyrolyl heterocycles was investigated. It was found that chelating ligand groups containing a strongly coordinating Nheterocyclic carbene donor led to the most effective catalysis and that an increase in the steric bulk of the ligand was detrimental to the catalyst efficiency.

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Section: ■ Results and Discussionmentioning

confidence: 76%

Iridium(III) Cp* Complexes for the Efficient Hydroamination of Internal Alkynes

et al. 2012

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“…Rh(I)/Rh(III) and Ir(I)/Ir(III) complexes have been demonstrated by us and others to be efficient catalysts for this transformation. 12,20,32,[40][41][42][43][44][45][46][47][48] We have found that small variations in donor ability of the ligands can lead to significant variations in the catalytic efficiency of the resulting metal complexes. 32,41,49 We tested a number of the Rh(I), Rh(III) and Ir(III) complexes containing the NHC-1,2,3-triazolyl donor ligands described here as catalysts for the intramolecular hydroamination of 4-pentyn-1-amine to form 2-methyl-1-pyrroline (Table 3).…”

Section: Catalysismentioning

confidence: 93%

Cationic Rh and Ir complexes containing bidentate imidazolylidene–1,2,3-triazole donor ligands: synthesis and preliminary catalytic studies

et al. 2013

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A series of new cationic Rh(I), Rh(III) and Ir(III) complexes containing hybrid bidentate N-heterocyclic carbene–1,2,3-triazolyl donor of general formulae [Rh(CaT)(COD)]BPh4 (2a–d), [Rh(CaT)(CO)2]BPh4 (3a–d) and [M(CaT)(Cp*)Cl]BPh4 (M = Rh, 4a–d; M = Ir, 5a–c), where CaT = bidentate N-heterocyclic carbene–triazolyl ligands, COD = 1,5-cyclooctadiene and Cp* = 1,2,3,4,5-pentamethylcyclopentadienyl, were synthesised. The imidazolium–1,2,3-triazolyl pre-ligands (1a–c and 1e–i) were readily prepared using the Cu(I) catalysed ‘click reaction’ between phenyl azide or benzyl azides with propargyl functionalised imidazolium salts. The single crystal solid state structures of complexes 2a–d; 3a–b; 4a–d and 5a–b confirm the bidentate coordination of the NHC–1,2,3-triazolyl ligand with the NHC coordinating via the ‘normal’ C2-carbon and the 1,2,3-triazolyl donor coordinating via the N3′ atom to form six membered metallocycles. These complexes are the first examples of Rh and Ir complexes containing the hybrid NHC–1,2,3-triazolyl ligands which exhibit a bidentate coordination mode. A number of these complexes showed limited efficiency as catalysts for the intramolecular hydroamination of 4-pentyn-1-amine to 2-methylpyrroline.

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“…By taking advantage of the observed reactivity trends during catalyst development, Field and Messerle [200] were successful in applying these catalyst systems to benzo(dipyrrole) synthesis (Scheme 15.28). Ogata and Fukuzawa [201] also developed dinuclear Ir and Rh systems with NHCs for the related intramolecular hydroamination reaction to give substituted indole products. Intermolecular alkyne hydroamination was recently investigated by Otero and coworkers [202], where they have used a cationic Rh complex ligated with easily varied iminopyridine ligands (31).…”

Section: Catalysts For Alkyne Substratesmentioning

confidence: 99%