Oxidative addition reactions and stereochemistry on rhodium/4,5-bis(2-oxazolinyl)xanthene complexes

Uchimura, Hirofumi; Ito, Junichi; Iwasa, Seiji; Nishiyama, Hisao

doi:10.1016/j.jorganchem.2006.04.040

Cited by 9 publications

(2 citation statements)

References 16 publications

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“…Nishiyama et al , described the synthesis, characterization, and catalytic activity of rhodacyclopentadienes 97a , b and 98 , containing tridentate ligands such as N , N , N -type ligand (pybox: 2,6-bis(2-oxazoline)pyridine) and xanthene-based N , O , N -type ligand (Xabox: 4,5-bis(2-oxazolinyl)xanthene). The authors first isolated a 68% yield of rhodacyclopentadiene 97a when a 1:2 mixture of [Rh(coe) 2 Cl] 2 (coe = cyclooctene) and pybox ligand reacted with diyne 61a in THF at 25–30 °C.…”

Section: [2 + 2 + 2] Cycloaddition Of Three Alkynesmentioning

confidence: 99%

Mechanistic Studies of Transition-Metal-Catalyzed [2 + 2 + 2] Cycloaddition Reactions

2020

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The development of catalytic methodologies involving the formation of C−C bonds to enable the generation of cyclic systems constitutes a field of great relevance in synthetic organic chemistry. One paradigmatic process to accomplish this goal efficiently is the transition-metal-catalyzed [2 + 2 + 2] cycloaddition reaction, since it permits the formation of a wide range of highly functionalized 6-membered carbo-and heterocyclic molecules in a single step with high efficiency and perfect atom economy. A key feature of these transformations is the mechanistic pathway that they follow, since a deep knowledge of this mechanism may enable us to understand and improve the efficiency of the reaction. This review covers the mechanistic aspects, studied both from theoretical and experimental points of view, of the transition-metal-catalyzed [2 + 2 + 2] cycloaddition reaction involving all kinds of unsaturated substrates with metals such as Co, Ni, Ru, Rh, Ir, Pd, Zr, Ti, Ta, and Nb. A thorough overview is undertaken, from the seminal studies until the present day, of the key mechanistic aspects that influence the reactivity and selectivity of the reaction, comparing the involvement of different unsaturated substrates as well as the different transition metals used.

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Section: [2 + 2 + 2] Cycloaddition Of Three Alkynesmentioning

confidence: 99%

Mechanistic Studies of Transition-Metal-Catalyzed [2 + 2 + 2] Cycloaddition Reactions

2020

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“…A wide range of substrates have been investigated, including diynes and alkynes with high degree of steric hindrance, 40 perfluoroalkylacetylenes, 41 glycoside units bearing bis-propargyl ethers, 42 1-alkynylphosphine sulphides, 43 propargyl glycine aminoacids, 44 as well as synthetic equivalents of alkynes like enol ethers/acetates 45 or (Z)-(2-bromovinyl)trifluoroborate, 46 and even solid-supported diynes. 47 In addition, several rhodium(I) complexes were found to be very efficient as catalysts, obtained by treatment of a rhodium(I) precursor with proper ligands: 4,5-bis (2oxazolinyl)xanthene (Xabox), 48 N-phosphino t-butylsulfinamides (PNSO), 49 tris(meta-sulfonatophenyl)phosphine trisodium salt (tppts) 50 and a 2,2′-bipyridine cationic derivative 51 (both watersoluble), and more recently also N-heterocyclic carbenes supported on silica. 52 A very exciting application of Rh-catalyzed [2+2+2] cycloadditions is the enantioselective synthesis of axially chiral compounds bearing phthalan moieties, performed in the presence of enantiopure chiral ligands.…”

Section: [2+2+2] Cyclotrimerization Of Alkynesmentioning

confidence: 99%

Cyclization Reactions for the Synthesis of Phthalans and Isoindolines

Albano

Aronica

2018

Synthesis

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Oxygen and nitrogen heterocycles are present in a vast number of natural substrates and biologically active molecules. In particular, phthalan and isoindoline subunits are found in many classes of products such as antibiotics, antioxidants, antimycotics, pigments, and fluorophores. Therefore several procedures dedicated to the construction of these heterocycles have been developed. In this review, a detailed analysis of the literature data regarding the synthesis of these nuclei via cyclization reactions is reported.1 Introduction2 Phthalans2.1 Oxa-Pictet–Spengler Reaction2.2 Garratt–Braverman Cyclization2.3 Diels–Alder and Related Reactions2.4 [2+2+2] Cyclotrimerization of Alkynes2.5 Cycloetherification of ortho-Substituted Aromatics2.6 Tandem Carbonylative Sonogashira Coupling–Cyclization Reactions3 Isoindolines3.1 Amination of Dihalides3.2 Intramolecular Hydroamination3.3 Diels–Alder and Related Reactions3.4 [2+2+2] Cycloaddition Reactions3.5 Tandem Carbonylative Sonogashira Coupling–Cyclization Reactions4 Conclusions

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Direct Detection of Key Intermediates in Rhodium(I)‐Catalyzed [2+2+2] Cycloadditions of Alkynes by ESI‐MS

Parera

Dachs

Solà

et al. 2012

Chemistry A European J

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The mechanism of the Rh-catalysed [2+2+2] cycloaddition reaction of diynes with monoynes has been examined using ESI-MS and ESI-CID-MS analysis. The catalytic system used consisted of the combination of a cationic rhodium(I) complex with bisphosphine ligands, which generates highly active complexes that can be detected by ESI(+) experiments. ESI-MS on-line monitoring has allowed the detection for the first time of all of the intermediates in the catalytic cycle, supporting the mechanistic proposal based mainly on theoretical calculations. For all ESI-MS experiments, the structural assignments of ions are supported by tandem mass spectrometry analyses. Computer model studies based on density functional theory (DFT) support the structural proposal made for the monoyne insertion intermediate. The collective studies provide new insight into the reactivity of cationic rhodacyclopentadienes, which should facilitate the design of related rhodium-catalysed C-C couplings.

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Oxidative addition reactions and stereochemistry on rhodium/4,5-bis(2-oxazolinyl)xanthene complexes

Cited by 9 publications

References 16 publications

Mechanistic Studies of Transition-Metal-Catalyzed [2 + 2 + 2] Cycloaddition Reactions

Mechanistic Studies of Transition-Metal-Catalyzed [2 + 2 + 2] Cycloaddition Reactions

Cyclization Reactions for the Synthesis of Phthalans and Isoindolines

Direct Detection of Key Intermediates in Rhodium(I)‐Catalyzed [2+2+2] Cycloadditions of Alkynes by ESI‐MS

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Oxidative addition reactions and stereochemistry on rhodium/4,5-bis(2-oxazolinyl)xanthene complexes

Cited by 9 publications

References 16 publications

Mechanistic Studies of Transition-Metal-Catalyzed [2 + 2 + 2] Cycloaddition Reactions

Mechanistic Studies of Transition-Metal-Catalyzed [2 + 2 + 2] Cycloaddition Reactions

Cyclization Reactions for the Synthesis of Phthalans and Isoindolines­

Direct Detection of Key Intermediates in Rhodium(I)‐Catalyzed [2+2+2] Cycloadditions of Alkynes by ESI‐MS

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Cyclization Reactions for the Synthesis of Phthalans and Isoindolines