Three-component indole synthesis using ortho-dihaloarenes

Palladium-catalyzed C-C and C-N bond-forming reactions are among the most versatile and powerful synthetic methods. For the last 15 years, N-heterocyclic carbenes (NHCs) have enjoyed increasing popularity as ligands in Pd-mediated cross-coupling and related transformations because of their superior performance compared to the more traditional tertiary phosphanes. The strong sigma-electron-donating ability of NHCs renders oxidative insertion even in challenging substrates facile, while their steric bulk and particular topology is responsible for fast reductive elimination. The strong Pd-NHC bonds contribute to the high stability of the active species, even at low ligand/Pd ratios and high temperatures. With a number of commercially available, stable, user-friendly, and powerful NHC-Pd precatalysts, the goal of a universal cross-coupling catalyst is within reach. This Review discusses the basics of Pd-NHC chemistry to understand the peculiarities of these catalysts and then gives a critical discussion on their application in C-C and C-N cross-coupling as well as carbopalladation reactions.

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“…Also in this case, the use of a stronger base (KOtBu, up to 2.5 equiv) was necessary. [224] 5. p-Allylpalladium Chemistry with NHC Ligands:…”

Section: G Organ Et Almentioning

confidence: 99%

Palladium Complexes of N‐Heterocyclic Carbenes as Catalysts for Cross‐Coupling Reactions—A Synthetic Chemist's Perspective

2007

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“…The use of ortho-haloaryl acetylenic bromides can lead to 2-aminoindole derivatives by a two-step procedure consisting of a copper-catalysed N-alkynylation followed by a separate palladium-catalysed N-arylation and subsequent cyclisation (Scheme 6). [10,17] The initial combination of an ortho-chloroiodobenzene with an alkyne in the presence of a mixed palladium/copper catalyst system afforded the key precursor 14. Scheme 6. An additional cascade process can be incorporated whereby the key ortho-alkynylhaloarene structure can be generated in situ.…”

Section: C-n Bond Formationmentioning

confidence: 99%

Cascade Palladium‐ and Copper‐Catalysed Aromatic Heterocycle Synthesis: The Emergence of General Precursors

Ball

Willis

2012

Eur J Org Chem

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Several privileged starting materials that allow access to a variety of different heterocyclic scaffolds through judicious choice of reaction conditions (and coupling partner) have emerged. This microreview focuses on the development and use of four of these starting material types in cascade reactions involving the palladium‐ or copper‐catalysed formation of aromatic carbon–nitrogen, carbon–oxygen or carbon–sulfur bonds.

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“…Here, multicomponent coupling reactions (26), which directly yield the desired products via domino (27) or tandem reaction sequences after significant advantages (28Á32) over stepwise procedures (33).…”

Section: Introductionmentioning

confidence: 99%

A green methodology for one-pot synthesis of polysubstituted-tetrahydropyrimidines using PEG

Kidwai

Mishra

Bhatnagar

et al. 2011

Green Chemistry Letters and Reviews

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Three-component indole synthesis using ortho-dihaloarenes

Cited by 110 publications

References 20 publications

Palladium Complexes of N‐Heterocyclic Carbenes as Catalysts for Cross‐Coupling Reactions—A Synthetic Chemist's Perspective

Palladium Complexes of N‐Heterocyclic Carbenes as Catalysts for Cross‐Coupling Reactions—A Synthetic Chemist's Perspective

Cascade Palladium‐ and Copper‐Catalysed Aromatic Heterocycle Synthesis: The Emergence of General Precursors

A green methodology for one-pot synthesis of polysubstituted-tetrahydropyrimidines using PEG

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