Synthesis, Structure, and Reactivity of a Palladium Hydrazonato Complex: A New Type of Reductive Elimination Reaction To Form C−N Bonds and Catalytic Arylation of Benzophenone Hydrazone

Hartwig, John F.

doi:10.1002/(sici)1521-3773(19980817)37:15<2090::aid-anie2090>3.0.co;2-a

Cited by 163 publications

(4 citation statements)

References 13 publications

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“…Hartwig disclosed the first method for the N-arylation of benzophenone hydrazone with aryl bromides in the presence of an L9 -based catalyst. 438 Shortly thereafter, Buchwald and co-workers demonstrated a broad-scope method and the practicality of benzophenone hydrazone coupling in a variant of the Fischer indole synthesis that avoids the need for toxic and unstable arylhydrazine precursors. 439 Other examples of the coupling of benzophenone hydrazone have been shown using MePhos-, 440 , 441 L7 -, 439 L10 -, 442 and L17 -based 443 palladium catalysts.…”

Section: Hydrazine and Hydrazine Derivativesmentioning

confidence: 99%

Applications of Palladium-Catalyzed C–N Cross-Coupling Reactions

2016

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Pd-catalyzed cross-coupling reactions that form C–N bonds have become useful methods to synthesize anilines and aniline derivatives, an important class of compounds throughout chemical research. A key factor in the widespread adoption of these methods has been the continued development of reliable and versatile catalysts that function under operationally simple, user-friendly conditions. This review provides an overview of Pd-catalyzed N-arylation reactions found in both basic and applied chemical research from 2008 to the present. Selected examples of C–N cross-coupling reactions between nine classes of nitrogen-based coupling partners and (pseudo)aryl halides are described for the synthesis of heterocycles, medicinally relevant compounds, natural products, organic materials, and catalysts.

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Section: Hydrazine and Hydrazine Derivativesmentioning

confidence: 99%

Applications of Palladium-Catalyzed C–N Cross-Coupling Reactions

2016

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“…However, this reaction occurred in higher yields for complexes containing chelating ligands. 33,34 For example, Scheme 7 shows that reductive elimination of N-arylpyrrole from PPh 3 complexes occurred in modest yield and at high temperatures, while reductive elimination from DPPF-ligated palladium complexes occurred in high yields.…”

Section: Reductive Elimination Of Aminesmentioning

confidence: 99%

Carbon−Heteroatom Bond-Forming Reductive Eliminations of Amines, Ethers, and Sulfides

1998

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Elementary transition metal-mediated reactions that form and cleave the bonds of organic molecules are the foundation of homogeneous catalysis. Such bond cleavage and formation often occurs by oxidative addition and reductive elimination. As shown in Scheme 1, these two reactions are essentially the same process in opposite directions: oxidative addition increases the oxidation state of the metal by two, decreases the d-electron count by two, and increases the overall number of valence electrons by two, while reductive elimination inflicts the opposite two-electron changes. Thermodynamic factors dictate whether a complex will undergo elimination or addition.The formation of carbon-hydrogen and carboncarbon bonds by reductive elimination is now common. Catalytic hydrogenation of alkenes, hydroformylation, alkene arylation (Heck reaction), and cross-coupling processes all involve C-H and C-C bond-forming reductive eliminations. The formation of carbon-heteroatom bonds by reductive elimination is less common, and just five years ago reductive elimination reactions that form C-O, C-N, and C-S bonds in ethers, amines, and sulfides had not been observed directly. It was unclear whether a kinetic barrier prevented these classes of reductive elimination, whether these eliminations were disfavored thermodynamically, or whether appropriate compounds to observe these reactions simply had not been prepared.During the past five years, palladium-catalyzed chemistry that produces arylamines from aryl halides and either primary or secondary amines has been developed, 1-4 and a catalytic cycle that is supported by detailed mechanistic studies 5 is provided in Scheme 2. It seemed likely that the amination process, first reported with tin amides by Kosugi and Migita over 10 years ago, 6,7 involved reductive elimination of amine. It, therefore, seemed to the members of my research group that the generation of stable palladium amido aryl complexes would allow for the direct observation of C-N bond-forming reductive elimination of amines.In addition, similar palladium-and nickel-catalyzed reactions that form aryl sulfides have been reported, [8][9][10][11][12][13][14] and again, generation of stable thiolato aryl complexes would allow for the direct observation of C-S bondforming reductive elimination of sulfides. Information on how these reactions occur might lead to improvements upon the catalytic formation of amines and sulfides. Finally, these studies may reveal systems that would undergo reductive elimination chemistry to form the C-O bonds in aryl ethers. As a result of this work, palladiumand nickel-catalyzed amination of aryl halides has become a general process 1-4 and new chemistry that forms aryl ethers has been developed recently. [15][16][17][18][19] Reviews of the catalytic carbon-heteroatom bond-forming coupling processes have been published recently. [20][21][22] This Account describes work in my laboratory, along with related work from other groups, on the discovery of complexes that reductively eliminate amines, ethe...

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“…Palladium derivatives with monodentate hydrazonato ligands are rare and, to our knowledge, only one structurally characterized complex of this type has been reported before. 13 Complexes 5 and 6 were isolated in good yields and characterized. Fig.…”

Section: Resultsmentioning

confidence: 99%