scholarly journals Divergent Rhodium-Catalyzed Electrochemical Vinylic C–H Annulation of Acrylamides with Alkynes

2020 ◽  
Author(s):  
Yi-Kang Xing ◽  
Xin-Ran Chen ◽  
Qi-Liang Yang ◽  
Shuoqing Zhang ◽  
Haiming Guo ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Transition Metal ◽  
Dft Calculations ◽  
Reductive Elimination ◽  
Electrochemical Process ◽  
Membered Ring ◽  
Environmentally Benign ◽  
Rhodium Catalysis ◽  
Undivided Cell ◽  
Metal Catalyzed

Abstract A Rh-catalyzed electrochemical vinylic C–H annulation of acrylamides with alkynes has been developed in an undivided cell, affording cyclic products in good to excellent yield. Divergent syntheses of α-pyridones and cyclic imidates are accomplished by employing N-phenyl acrylamides and N-tosyl acrylamides as substrates, respectively. Additionally, excellent regioselectivities are achieved when using unsymmetrical alkynes. This electrochemical process is environmentally benign compared to traditional transition metal-catalyzed C–H annulations because it avoids the use of stoichiometric metal oxidants. DFT calculations elucidated the reaction mechanism and origins of substituent-controlled chemoselectivity. The sequential C–H activation and alkyne insertion under rhodium catalysis leads to the seven-membered ring vinyl-rhodium intermediate. This intermediate undergoes either the classic neutral concerted reductive elimination to produce α-pyridones, or the ionic stepwise pathway to produce cyclic imidates.

scholarly journals Divergent rhodium-catalyzed electrochemical vinylic C–H annulation of acrylamides with alkynes

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yi-Kang Xing ◽  
Xin-Ran Chen ◽  
Qi-Liang Yang ◽  
Shuo-Qing Zhang ◽  
Hai-Ming Guo ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Dft Calculations ◽  
Small Molecules ◽  
Reductive Elimination ◽  
Electrochemical Process ◽  
Membered Ring ◽  
Biologically Active ◽  
Environmentally Benign ◽  
Rhodium Catalysis ◽  
Metal Catalyzed

Abstractα-Pyridones and α-pyrones are ubiquitous structural motifs found in natural products and biologically active small molecules. Here, we report an Rh-catalyzed electrochemical vinylic C–H annulation of acrylamides with alkynes, affording cyclic products in good to excellent yield. Divergent syntheses of α-pyridones and cyclic imidates are accomplished by employing N-phenyl acrylamides and N-tosyl acrylamides as substrates, respectively. Additionally, excellent regioselectivities are achieved when using unsymmetrical alkynes. This electrochemical process is environmentally benign compared to traditional transition metal-catalyzed C–H annulations because it avoids the use of stoichiometric metal oxidants. DFT calculations elucidated the reaction mechanism and origins of substituent-controlled chemoselectivity. The sequential C–H activation and alkyne insertion under rhodium catalysis leads to the seven-membered ring vinyl-rhodium intermediate. This intermediate undergoes either the classic neutral concerted reductive elimination to produce α-pyridones, or the ionic stepwise pathway to produce cyclic imidates.

Well-defined nickel(II) tetrazole-saccharinate complex as homogeneous catalyst on the reduction of aldehydes: scope and reaction mechanism

2020 ◽  
Vol 92 (1) ◽  
pp. 151-166 ◽  
Author(s):  
Luís M. T. Frija ◽  
Bruno G. M. Rocha ◽  
Maxim L. Kuznetsov ◽  
Lília I. L. Cabral ◽  
M. Lurdes S. Cristiano ◽  
...  
Keyword(s):  
Experimental Data ◽  
Reaction Mechanism ◽  
Transition Metal ◽  
Dft Calculations ◽  
Microwave Power ◽  
Low Temperatures ◽  
Nickel Complex ◽  
Transition Metal Catalysts ◽  
Homogeneous Catalyst ◽  
First Time

AbstractA new (tetrazole-saccharin)nickel complex is shown to be a valuable catalyst for the hydrosilative reduction of aldehydes under microwave radiation at low temperatures. With typical 1 mol% content of the catalyst (microwave power range of 5–15 W) most reactions are complete within 30 min. The Ni(II)-catalyzed reduction of aldehydes, with a useful scope, was established for the first time by using this catalyst, and is competitive with the most effective transition-metal catalysts known for such transformation. The catalyst reveals tolerance to different functional groups, is air and moisture stable, and is readily prepared in straightforward synthetic steps. Supported by experimental data and DFT calculations, a plausible reaction mechanism involving the new catalytic system is outlined.

Transition-metal-catalyzed reactions involving reductive elimination between dative ligands and covalent ligands

2020 ◽  
Vol 49 (5) ◽  
pp. 1487-1516 ◽  
Author(s):  
Tianxiao Jiang ◽  
Haocheng Zhang ◽  
Yongzheng Ding ◽  
Suchen Zou ◽  
Rui Chang ◽  
...  
Keyword(s):  
Transition Metal ◽  
Reductive Elimination ◽  
Elementary Step ◽  
Transition Metal Catalyzed ◽  
Catalyzed Reactions ◽  
Metal Catalyzed ◽  
Covalent Ligands

This review summarizes transition-metal catalyzed reactions with reductive elimination between covalent ligands and dative ligands as the key elementary step.

Cascade Reaction of Camphor-Derived Diynes with Transition Metal Compounds

1999 ◽  
Vol 54 (6) ◽  
pp. 725-733 ◽  
Author(s):  
M. Fernanda N. N. Carvalho ◽  
Armando J. L. Pombeiro ◽  
Gabriele Wagner ◽  
Bjørn Pedersen ◽  
Rudolf Herrmann
Keyword(s):  
Reaction Mechanism ◽  
Transition Metal ◽  
Hydroxy Group ◽  
Bond Cleavage ◽  
Cascade Reaction ◽  
Membered Ring ◽  
Transition Metal Compounds ◽  
Metal Compounds ◽  
Ring Enlargement ◽  
Copper Gold

Platinum(II) catalyzes the isomerization of camphor sulfonamide diynes in a cascade reaction involving annulation of a five-membered ring to the camphor skeleton, ring-enlargement by C-C bond cleavage, reduction of sulfur(VI) to sulfur(IV), and oxidation of a hydroxy group to a ketone. The reactions of the diynes with other transition metal compounds were also studied. Copper, gold and rhenium give final products similar to those obtained with simple Brønsted acids or halogens, mainly by annulation o f a five-membered ring to the camphor moiety, accompanied by reduction of a sulfonamide to a sulfinamide group, but lacking the ring-enlargement step. Palladium(II) occupies an intermediate position as both types o f products are obtained. The reaction mechanism and intermediates are discussed

Cu(I)-Bis(phosphine) Dioxides as catalysts for the Enantioselective α-Arylation of Carbonyl Compounds

Synlett ◽  
2021 ◽  
Author(s):  
Margarita Escudero-Casao ◽  
Giulia Licini ◽  
Manuel Orlandi
Keyword(s):  
Reaction Mechanism ◽  
Transition Metal ◽  
Catalytic System ◽  
Carbonyl Compounds ◽  
Research Area ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

The transition metal catalyzed α-arylation of carbonyl compounds was first reported by Buchwald and Hartwig in 1997. This transformation has been used and studied extensively over the last two decades. Enantioselective variants were also developed that allow for controlling the product stereochemistry. However, these suffer several limitations in the context of formation of tertiary stereocenters. Presented here is our group’s contribution to this research area. The chiral Cu-bis(phosphine) dioxides catalytic system that we reported allowed accessing the enantioselective α-arylation of ketones that were not suitable for this transformation before in good yields and er up to 97.5:2.5. Preliminary insight and speculation concerning the reaction mechanism involving the unusual pairing of bis(phosphine) dioxides with transition metal catalysts is also given.

Copper-catalyzed N-(hetero)arylation of amino acids in water

RSC Advances ◽  
2016 ◽  
Vol 6 (99) ◽  
pp. 96762-96767 ◽  
Author(s):  
Krishna K. Sharma ◽  
Meenakshi Mandloi ◽  
Neha Rai ◽  
Rahul Jain
Keyword(s):  
Amino Acids ◽  
Transition Metal ◽  
Cost Effective ◽  
Environmentally Benign ◽  
Cost Effective Method ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

A transition metal-catalyzed, environmentally benign, rapid and cost-effective method for the N-(hetero)arylation of zwitterionic amino acids in water is reported.

Development of transition-metal-catalyzed cycloaddition reactions leading to polycarbocyclic systems

2011 ◽  
Vol 83 (3) ◽  
pp. 495-506 ◽  
Author(s):  
Moisés Gulías ◽  
Fernando López ◽  
José L. Mascareñas
Keyword(s):  
Density Functional Theory ◽  
Transition Metal ◽  
Dft Calculations ◽  
Density Functional ◽  
Conjugated Dienes ◽  
Ni Catalysts ◽  
Functional Theory ◽  
Different Types ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

We present a compilation of methodologies developed in our laboratories to assemble polycyclic structures containing small- and medium-sized cycles, relying on the use of transition-metal-catalyzed (TMC) cycloadditions. First, we discuss the use of alkylidenecyclopropanes (ACPs) as 3C-atom partners, in particular in their Pd-catalyzed (3 + 2) cycloadditions with alkynes, alkenes, and allenes, reactions that lead to cyclopentane-containing polycyclic products in excellent yields. Then, we present the expansion of this chemistry to a (4 + 3) annulation with conjugated dienes, and to inter- and intramolecular (3 + 2 + 2) cycloadditions using external alkenes as additional 2C-π-systems. These reactions allow the preparation of different types of polycyclic structures containing cycloheptene rings, the topology of the products depending on the use of Pd or Ni catalysts. Finally, we include our more recent discoveries on the development of (4 + 3) and (4 + 2) intramolecular cyclo-additions of allenes and dienes, promoted by Pt and Au catalysts, and discuss mechanistic insights supported by experimental and density functional theory (DFT) calculations. An enantioselective version of the (4 + 2) cycloaddition with phosphoramidite Au(I) catalysts is also presented.

A metal-free method for facile synthesis of indanones via intramolecular hydroacylation of 2-vinylbenzaldehydes

2021 ◽  
Author(s):  
Guoxue He ◽  
Jinyu Ma ◽  
Jianhui Zhou ◽  
Chunpu Li ◽  
Hong Liu ◽  
...  
Keyword(s):  
Transition Metal ◽  
Environmentally Benign ◽  
Facile Synthesis ◽  
Metal Free ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

A facile method access to indanones was developed under metal- and additive-free conditions in which L-proline served as efficient and environmentally benign catalysts. Compared with previous indanones synthesis by transition-metal-catalyzed...

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