Mechanism of the Palladium‐Catalyzed Synthesis of Münchnones: The Role of Ligands in <i>N</i>‐Acyl Iminium Salt Carbonylation

Tjutrins, Jevgenijs; Dhawan, Rajiv; Lu, Yingdong; Arndtsen, Bruce A.

doi:10.1002/chem.201603400

Cited by 6 publications

(2 citation statements)

References 80 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Another type of analogous species that is proposed as the key reactive intermediate for palladium-catalyzed aldehyde amidocarbonylations has been prepared via the oxidative addition of amide iminium to Pd(0) by Arndtsen and co-workers. − However, X-ray crystallography analysis of such species shows that a five-membered palladacycle is formed, in which the C–Pd bond is considerably shorter (2.00 Å vs 2.19 Å in our aminomethyl cyclopalladated complex). The discrepancy indicates that the electron-withdrawing effect imparted by the amide moiety would make the contribution of Pd-iminium resonance negligible. , Such structural characteristics obviously differ from those of our three-membered aminomethyl cyclopalladated complex. As a result, these five-membered palladacycle complexes can only undergo CO insertion to furnish amidocarbonylations for the efficient synthesis of amino acid derivatives and N- heterocycles. ,, In contrast, as shown in Scheme D, the contribution from both resonance forms of the aminomethyl cyclopalladated complex suggests that both the palladium center and the aminomethyl ligand can be regarded as electrophilic sites.…”

Section: Preparation Characterization and General Reaction Modescontrasting

confidence: 59%

“…The discrepancy indicates that the electron-withdrawing effect imparted by the amide moiety would make the contribution of Pd-iminium resonance negligible. 34,37 Such structural characteristics obviously differ from those of our three-membered aminomethyl cyclopalladated complex. As a result, these five-membered palladacycle complexes can only undergo CO insertion to furnish amidocarbonylations for the efficient synthesis of amino acid derivatives and N-heterocycles.…”

Section: Preparation Characterization and General Reaction Modescontrasting

confidence: 57%

See 1 more Smart Citation

Catalytic Reactions Directed by a Structurally Well-Defined Aminomethyl Cyclopalladated Complex

et al. 2021

View full text Add to dashboard Cite

Conspectus The introduction of N-containing moieties into feedstock molecules to build nitrogenated functional molecules has always been widely studied by the organic chemistry community. Progress in this field paves new roads to the synthesis of N-containing molecules, which are of significant importance in biological activities and play vital roles in pharmaceuticals and functional materials. Remarkable progress has been achieved in the field of transition metal-catalyzed C–N bond-forming reactions, typified by alkene hydroamination and the aza-Wacker reaction. However, the poisoning effect of electron-donating amine substrates on late transition metal catalysts presents a key impediment to these reactions, thus limiting the scope of amine substrates to electron-deficient amide derivatives. To address this problem, our group developed a palladium–aminomethyl complex with a three-membered palladacycle structure that allowed for the incorporation of electron-rich amine building blocks via C–C bond instead of C–N bond construction. This Account details the discovery of the well-defined aminomethyl cyclopalladated complex and recapitulates its applications for the catalysis of a series of aminomethylation reactions. We highlight how the understanding of the fundamental structural properties of the defined complex guided us toward tuning the reactivity of nucleophiles to initiate aminomethylation in different modes. Moreover, principles of designing and establishing further cascade reactions are also described. Aminomethyl cyclopalladated complexes can be prepared via the oxidative addition of aminals or N,O-acetals to Pd0 species. Thorough structural investigations by single-crystal X-ray diffraction analysis of the cyclopalladated complex suggest the presence of both aminomethylene–PdII (3-membered-ring) and Pd0–iminium (π-ligated) resonance forms, which indicates that both the palladium center and the methylene site are electrophilic. This is further verified by analysis of charge distribution. Two general types of reactions can be established, differing by the selective affinity of the nucleophiles to the two electrophilic positions, which is relevant to the “hardness suitability” of the nucleophiles with each electrophilic site. Softer nucleophiles such as alkenes prefer to attack the palladium center to initiate the reaction, mainly via migratory insertion into the Pd–C bond on the 3-membered ring with high strain. Through tandem β-hydride or reductive elimination, the Heck-type aminomethylation of styrenes, the aminomethylalkoxylation of electron-rich olefins, and even the aminomethylamination of allenes, dienes, enynes, and carbenoids with full atom-economy have been realized in line with this reaction mode. In contrast, harder nucleophiles tend to attack the harder electrophilic methylene site, leading to the aminomethylation of electron-deficient dienes. For secondary amines, a “C–N bond metathesis” process would be furnished through a reductive elimination, 1,3-proton transfer, and oxidative addition sequ...

show abstract

Section: Preparation Characterization and General Reaction Modescontrasting

confidence: 59%

Section: Preparation Characterization and General Reaction Modescontrasting

confidence: 57%

Catalytic Reactions Directed by a Structurally Well-Defined Aminomethyl Cyclopalladated Complex

et al. 2021

View full text Add to dashboard Cite

show abstract

An Efficient Protocol to Synthesize N‐Acyl‐enamides and ‐Imines by Pd‐Catalyzed Carbonylations

Wang

Neumann

Spannenberg

et al. 2018

Chemistry A European J

View full text Add to dashboard Cite

For the first time, the bidentate phosphinite ligand 1,2-bis(di-tert-butylphosphinoxy)ethane (tBu POCH CH OPtBu ) was synthesized. In the presence of this ligand, various N-acyl enamides were obtained in good yields and chemoselectivity by Pd-catalyzed carbonylation reaction of imines containing α-H. Meanwhile, imines without α-H could be transformed to N-acyl imines, which form highly hindered amides by straightforward addition of Grignard reagents.

show abstract

A Versatile Approach to Dynamic Amide Bond Formation with Imine Nucleophiles

Erguven

Keyzer

Arndtsen

2020

Chemistry A European J

Self Cite

View full text Add to dashboard Cite

Dynamic covalent chemistryh as rapidlyb ecome an importanta pproacht oa ccess supramolecular structures. While the products generatedi nt hese reactions are heldt ogether by covalent bonds, the reversible nature of the transformations can limit the utility of many these systems in creating robust materials.W ed escribe herein am ethodt of orm stable andc ommonly employed amideb onds by exploiting the reversible coupling of imines and acyl chlorides.T he reactione mploys easilya ccessible reagents, is dynamic under ambientc onditions, without catalysts, and can be trapped with simple hydrolysis. Thiso ffers an approach to create broad families of amide products under thermodynamic control,i ncluding the selective formation of amide macrocycles or polymers.Supporting information and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

show abstract

Mechanism of the Palladium‐Catalyzed Synthesis of Münchnones: The Role of Ligands in N‐Acyl Iminium Salt Carbonylation

Cited by 6 publications

References 80 publications

Catalytic Reactions Directed by a Structurally Well-Defined Aminomethyl Cyclopalladated Complex

Catalytic Reactions Directed by a Structurally Well-Defined Aminomethyl Cyclopalladated Complex

An Efficient Protocol to Synthesize N‐Acyl‐enamides and ‐Imines by Pd‐Catalyzed Carbonylations

A Versatile Approach to Dynamic Amide Bond Formation with Imine Nucleophiles

Contact Info

Product

Resources

About