Mechanistic Investigation of the Palladium-Catalyzed Decarboxylative Cyclization of γ-Methylidene-δ-valerolactones with Isocyanates: Kinetic Studies and Origin of the Site Selectivity in the Nucleophilic Attack at a (π-Allyl)palladium

2010 ◽  
Vol 132 (21) ◽  
pp. 7508-7513 ◽  
Author(s):  
Ryo Shintani ◽  
Takaoki Tsuji ◽  
Soyoung Park ◽  
Tamio Hayashi
Keyword(s):  
Kinetic Studies ◽  
Nucleophilic Attack ◽  
Site Selectivity ◽  
Mechanistic Investigation ◽  
Palladium Catalyzed ◽  
Decarboxylative Cyclization

Theoretical and experimental studies of palladium-catalyzed site-selective C(sp3)−H bond functionalization enabled by transient ligands

2017 ◽  
Author(s):  
Haibo Ge ◽  
Lei Pan ◽  
Piaoping Tang ◽  
Ke Yang ◽  
Mian Wang ◽  
...  
Keyword(s):  
Bond Activation ◽  
Theoretical Calculations ◽  
Experimental Studies ◽  
Bond Functionalization ◽  
Aliphatic Ketones ◽  
Site Selectivity ◽  
Mechanistic Investigation ◽  
Palladium Catalyzed ◽  
Metal Catalyzed ◽  
Site Selective

Transition metal-catalyzed selective C–H bond functionalization enabled by transient ligands has become an extremely attractive topic due to its economical and greener characteristics. However, catalytic pathways of this reaction process on unactivated sp<sup>3</sup> carbons of reactants have not been well studied yet. Herein, detailed mechanistic investigation on Pd-catalyzed C(sp<sup>3</sup>)–H bond activation with amino acids as transient ligands has been systematically conducted. The theoretical calculations showed that higher angle distortion of C(sp2)-H bond over C(sp3)-H bond and stronger nucleophilicity of benzylic anion over its aromatic counterpart, leading to higher reactivity of corresponding C(sp<sup>3</sup>)–H bonds; the angle strain of the directing rings of key intermediates determines the site-selectivity of aliphatic ketone substrates; replacement of glycine with β-alanine as the transient ligand can decrease the angle tension of the directing rings. Synthetic experiments have confirmed that β-alanine is indeed a more efficient transient ligand for arylation of β-secondary carbons of linear aliphatic ketones than its glycine counterpart.<br><br>

Theoretical and experimental studies of palladium-catalyzed site-selective C(sp3)−H bond functionalization enabled by transient ligands

2017 ◽  
Author(s):  
Haibo Ge ◽  
Lei Pan ◽  
Piaoping Tang ◽  
Ke Yang ◽  
Mian Wang ◽  
...  
Keyword(s):  
Bond Activation ◽  
Theoretical Calculations ◽  
Experimental Studies ◽  
Bond Functionalization ◽  
Aliphatic Ketones ◽  
Site Selectivity ◽  
Mechanistic Investigation ◽  
Palladium Catalyzed ◽  
Metal Catalyzed ◽  
Site Selective

Transition metal-catalyzed selective C–H bond functionalization enabled by transient ligands has become an extremely attractive topic due to its economical and greener characteristics. However, catalytic pathways of this reaction process on unactivated sp<sup>3</sup> carbons of reactants have not been well studied yet. Herein, detailed mechanistic investigation on Pd-catalyzed C(sp<sup>3</sup>)–H bond activation with amino acids as transient ligands has been systematically conducted. The theoretical calculations showed that higher angle distortion of C(sp2)-H bond over C(sp3)-H bond and stronger nucleophilicity of benzylic anion over its aromatic counterpart, leading to higher reactivity of corresponding C(sp<sup>3</sup>)–H bonds; the angle strain of the directing rings of key intermediates determines the site-selectivity of aliphatic ketone substrates; replacement of glycine with β-alanine as the transient ligand can decrease the angle tension of the directing rings. Synthetic experiments have confirmed that β-alanine is indeed a more efficient transient ligand for arylation of β-secondary carbons of linear aliphatic ketones than its glycine counterpart.<br><br>

Palladium-catalyzed C–H activation of anisole with electron-deficient auxiliary ligands: a mechanistic investigation

2020 ◽  
Vol 18 (30) ◽  
pp. 5857-5866 ◽  
Author(s):  
Xinyu Xu ◽  
Kezhi Chen
Keyword(s):  
Dft Calculations ◽  
Site Selectivity ◽  
Mechanistic Investigation ◽  
Palladium Catalyzed

In this work, the experimentally observed site-selectivity and ligand choice of Yu's meta-arylation reaction were rationalized through DFT calculations.

Ligand-Enabled γ-C(sp3)–H Olefination of Free Carboxylic Acids

2020 ◽  
Author(s):  
Kiron Kumar Ghosh ◽  
Alexander Uttry ◽  
Francesca Ghiringhelli ◽  
Arup Mondal ◽  
Manuel van Gemmeren
Keyword(s):  
Reaction Mechanism ◽  
Carboxylic Acids ◽  
Michael Addition ◽  
Kinetic Studies ◽  
Wide Range ◽  
Palladium Catalyzed

We report the ligand enabled C(sp3)–H activation/olefination of free carboxylic acids in the γ-position. Through an intramolecular Michael-addition, δ-lactones are obtained as products. Two distinct ligand classes are identified that enable the challenging palladium-catalyzed activation of free carboxylic acids in the γ-position. The developed protocol features a wide range of acid substrates and olefin reaction partners and is shown to be applicable on a preparatively useful scale. Insights into the underlying reaction mechanism obtained through kinetic studies are reported.<br>

scholarly journals Understanding the reaction mechanism of the regioselective piperidinolysis of aryl 1-(2,4-dinitronaphthyl) ethers in DMSO: Kinetic and DFT studies

2021 ◽  
Vol 46 ◽  
pp. 146867832110274
Author(s):  
Yasmen M Moghazy ◽  
Nagwa MM Hamada ◽  
Magda F Fathalla ◽  
Yasser R Elmarassi ◽  
Ezzat A Hamed ◽  
...  
Keyword(s):  
Carbon Atom ◽  
Density Functional ◽  
Function Analysis ◽  
Density Functional Theory Method ◽  
Activation Parameters ◽  
Kinetic Studies ◽  
Nucleophilic Attack ◽  
Common Mechanism ◽  
Slow Step ◽  
Rate Determining Step

Reactions of aryl 1-(2,4-dinitronaphthyl) ethers with piperidine in dimethyl sulfoxide at 25oC resulted in substitution of the aryloxy group at the ipso carbon atom. The reaction was measured spectrophotochemically and the kinetic studies suggested that the titled reaction is accurately third order. The mechanism is began by fast nucleophilic attack of piperidine on C1 to form zwitterion intermediate (I) followed by deprotonation of zwitterion intermediate (I) to the Meisenheimer ion (II) in a slow step, that is, SB catalysis. The regular variation of activation parameters suggested that the reaction proceeded through a common mechanism. The Hammett equation using reaction constant σo values and Brønsted coefficient value showed that the reaction is poorly dependent on aryloxy substituent and the reaction was significantly associative and Meisenheimer intermediate-like. The mechanism of piperidinolysis has been theoretically investigated using density functional theory method using B3LYP/6-311G(d,p) computational level. The combination between experimental and computational studies predicts what mechanism is followed either through uncatalyzed or catalyzed reaction pathways, that is, SB and SB-GA. The global parameters of the reactants, the proposed activated complexes, and the local Fukui function analysis explained that C1 carbon atom is the most electrophilic center of ether. Also, kinetics and theoretical calculation of activation energies indicated that the mechanism of the piperidinolysis passed through a two-step mechanism and the proton transfer process was the rate determining step.

Palladium-catalyzed C1-vinylation of β-naphthols with α-trifluoromethyl allyl carbonates: One-pot access to naphtho[2,1-b]furans

2021 ◽  
Author(s):  
Chiliveru Priyanka ◽  
Muppidi Subbarao ◽  
Nagender Punna
Keyword(s):  
Nucleophilic Attack ◽  
One Pot ◽  
Palladium Catalyzed

Highly regio- and stereoselective palladium-catalyzed C1-vinylation of β-naphthols (2) has been reported using easily accessible CF3-allyl carbonates (1). The regioselective nucleophilic -attack of CF3-π-allyl-Pd-intermediate is the key to furnish (Z)-CF3-vinylnaphthols...

Non-directed highly para-selective C-H functionalization of TIPS-protected phenols promoted by a proton shuttle

2021 ◽  
Author(s):  
Jingyao Geng ◽  
Zhang Fang ◽  
Guangliang Tu ◽  
Yingsheng Zhao
Keyword(s):  
Bioactive Molecules ◽  
Protecting Group ◽  
Mechanism Study ◽  
Phenol Derivatives ◽  
Site Selectivity ◽  
Palladium Catalyzed ◽  
Direct Functionalization ◽  
Poor Site ◽  
Site Selective ◽  
First Time

Abstract Palladium-catalyzed non-directed C-H functionalization provides an efficient approach for direct functionalization of arenes, but it usually suffers from poor site selectivity, limiting its wide application. Herein, it is reported for the first time that the proton shuttle of 3,5-dimethyladamantane-1-carboxylic acid (1-DMAdCO2H) can affect the site selectivity during the C-H activation step in palladium-catalyzed non-directed C-H functionalization, leading to highly para-selective C-H olefination of TIPS-protected phenols. This transformation displayed good generality in realizing various other para-selective C-H functionalization reactions such as hydroxylation, halogenation, and allylation reactions. A wide variety of phenol derivatives including bioactive molecules of triclosan, thymol, and propofol, were compatible substrates, leading to the corresponding para-selective products in moderate to good yields. A preliminary mechanism study revealed that the spatial repulsion factor between proton shuttle and bulky protecting group resulted in the selective C-H activation at the less sterically hindered para-position. This new model non-directed para-selective C-H functionalization can provide a straightforward route for remote site-selective C-H activations.

Palladium-Catalyzed Heck/[4+1] Decarboxylative Cyclization Cascade to Access Diverse Heteropolycycles by α-Bromoacrylic Acids as C1 Insertion Units

2021 ◽  
Author(s):  
Minghao Zhang ◽  
Fengru Zhou ◽  
Xinyu Xuchen ◽  
Liwei Zhou ◽  
Guobo Deng ◽  
...  
Keyword(s):  
Aryl Iodides ◽  
Palladium Catalyzed ◽  
Decarboxylative Cyclization

A novel palladium-catalyzed Heck/[4+1] decarboxylative cyclization cascade of alkene-tethered aryl iodides with α-bromoacrylic acids is reported. This strategy employs α-bromoacrylic acids as a new C1 synthon to assemble diverse heteropolycycles,...

Palladium-Catalyzed Anti-Markovnikov Oxidation of Aromatic and Aliphatic Alkenes to Terminal Acetals and Aldehydes

Synthesis ◽  
2020 ◽  
Author(s):  
Yasuyuki Ura
Keyword(s):  
Organic Compounds ◽  
Catalytic System ◽  
Recent Progress ◽  
Short Review ◽  
Nucleophilic Attack ◽  
Reaction Conditions ◽  
Terminal Alkenes ◽  
Palladium Catalyzed ◽  
Substrate Addition ◽  
Cyclic Alkenes

AbstractCatalytic anti-Markovnikov (AM) oxidation of terminal alkenes can provide terminally oxyfunctionalized organic compounds. This short review mainly summarizes our recent progress on the Pd-catalyzed AM oxidations of aromatic and aliphatic terminal alkenes to give terminal acetals (oxidative acetalization) and aldehydes (Wacker-type oxidation), along with related reports. These reactions demonstrate the efficacy of the PdCl2(MeCN)2/CuCl/electron-deficient cyclic alkenes/O2 catalytic system. Notably, electron-deficient cyclic alkenes such as p-benzoquinones (BQs) and maleimides are key additives that facilitate nucleophilic attack of oxygen nucleophiles on coordinated terminal alkenes and enhance the AM selectivity. BQs also function to oxidize Pd(0) depending on the reaction conditions. Several other factors that improve the AM selectivity, such as the steric demand of the nucleo­philes, slow substrate addition, and halogen-directing groups, are also discussed.1 Introduction2 Anti-Markovnikov Oxidation of Aromatic Alkenes to Terminal Acetals­3 Anti-Markovnikov Oxidation of Aromatic Alkenes to Aldehydes4 Anti-Markovnikov Oxidation of Aliphatic Alkenes to Terminal Acetals­5 Anti-Markovnikov Oxidation of Aliphatic Alkenes to Aldehydes6 Conclusion

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