scholarly journals The Mechanism of Rhodium Catalyzed Allylic C–H Amination

2019 ◽  
Author(s):  
Robert Harris ◽  
Jiyong Park ◽  
Taylor Nelson ◽  
Nafees Iqbal ◽  
Daniel Salgueiro ◽  
...  
Keyword(s):  
Acid Catalyst ◽  
Reductive Elimination ◽  
Quantum Mechanical ◽  
Allylic Amination ◽  
Reaction Conditions ◽  
Allyl Complex ◽  
Acetate Ligand ◽  
Amination Reaction ◽  
Lewis Acid Catalyst

The mechanism of catalytic allylic C–H amination reactions promoted by Cp*Rh complexes is reported. Reaction kinetics experiments, stoichiometric studies, and DFT calculations demonstrate that allylic C–H activation to generate a Cp*Rh(π-allyl) complex is viable under mild reaction conditions. The role of external oxidant in the catalytic cycle is elucidated. Quantum mechanical calculations, stoichiometric reactions, and cyclic voltammetry<b></b>experiments support an oxidatively induced reductive elimination process of the allyl fragment with an acetate ligand. Lastly, evidences supporting the amination of an allylic acetate intermediate is presented. Both nucleophilic substitution catalyzed by Ag<sup>+</sup>that behaves as a Lewis acid catalyst and an inner-sphere amination catalyzed by Cp*Rh are shown to be viable for the last step of the allylic amination reaction.

scholarly journals The Mechanism of Rhodium Catalyzed Allylic C–H Amination

2019 ◽  
Author(s):  
Robert Harris ◽  
Jiyong Park ◽  
Taylor Nelson ◽  
Nafees Iqbal ◽  
Daniel Salgueiro ◽  
...  
Keyword(s):  
Acid Catalyst ◽  
Reductive Elimination ◽  
Quantum Mechanical ◽  
Allylic Amination ◽  
Reaction Conditions ◽  
Allyl Complex ◽  
Acetate Ligand ◽  
Amination Reaction ◽  
Lewis Acid Catalyst

The mechanism of catalytic allylic C–H amination reactions promoted by Cp*Rh complexes is reported. Reaction kinetics experiments, stoichiometric studies, and DFT calculations demonstrate that allylic C–H activation to generate a Cp*Rh(π-allyl) complex is viable under mild reaction conditions. The role of external oxidant in the catalytic cycle is elucidated. Quantum mechanical calculations, stoichiometric reactions, and cyclic voltammetry<b></b>experiments support an oxidatively induced reductive elimination process of the allyl fragment with an acetate ligand. Lastly, evidences supporting the amination of an allylic acetate intermediate is presented. Both nucleophilic substitution catalyzed by Ag<sup>+</sup>that behaves as a Lewis acid catalyst and an inner-sphere amination catalyzed by Cp*Rh are shown to be viable for the last step of the allylic amination reaction.

scholarly journals 1,3-Dioxolan-4-Ones as Promising Monomers for Aliphatic Polyesters: Metal-Free, in Bulk Preparation of PLA

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2396
Author(s):  
Stefano Gazzotti ◽  
Marco Aldo Ortenzi ◽  
Hermes Farina ◽  
Alessandra Silvani
Keyword(s):  
Molecular Weight ◽  
Thermal Properties ◽  
Acid Catalyst ◽  
Monomer Conversion ◽  
Reaction Conditions ◽  
Aliphatic Polyesters ◽  
Metal Free ◽  
Weight Growth ◽  
Double Activation

The first example of solvent-free, organocatalyzed, polymerization of 1,3-dioxolan-4-ones, used as easily accessible monomers for the synthesis of polylactic acid (PLA), is described here. An optimization of reaction conditions was carried out, with p-toluensulfonic acid emerging as the most efficient Brønsted acid catalyst. The reactivity of the monomers in the tested conditions was studied following the monomer conversion by 1H NMR and the molecular weight growth by SEC analysis. A double activation polymerization mechanism was proposed, pointing out the key role of the acid catalyst. The formation of acetal bridges was demonstrated, to different extents depending on the nature of the aldehyde or ketone employed for lactic acid protection. The polymer shows complete retention of stereochemistry, as well as good thermal properties and good polydispersity, albeit modest molecular weight.

ChemInform Abstract: Novel Role of Carbon Monoxide as a Lewis Acid Catalyst for Friedel-Crafts Reaction.

ChemInform ◽  
2010 ◽  
Vol 32 (52) ◽  
pp. no-no
Author(s):  
Sensuke Ogoshi ◽  
Hiromitsu Nakashima ◽  
Kazumasa Shimonaka ◽  
Hideo Kurosawa
Keyword(s):  
Carbon Monoxide ◽  
Lewis Acid ◽  
Acid Catalyst ◽  
Lewis Acid Catalyst

Zirconyl Nitrate as an Efficient Catalyst for Facile Synthesis of 2-Aryl-2,3-dihydroquinolin-4(1H)-one Derivatives in Aqueous ­Medium

Synlett ◽  
2017 ◽  
Vol 29 (02) ◽  
pp. 235-237
Author(s):  
Amarsinha Gorepatil ◽  
Pratapsinha Gorepatil ◽  
Mahadev Gaikwad ◽  
Dattakumar Mhamane ◽  
Ajit Phadkule ◽  
...  
Keyword(s):  
Aqueous Medium ◽  
Intramolecular Cyclization ◽  
Lewis Acid ◽  
Efficient Method ◽  
Acid Catalyst ◽  
Facile Synthesis ◽  
Zirconyl Nitrate ◽  
Reaction Conditions ◽  
Efficient Catalyst ◽  
Lewis Acid Catalyst

A simple, green, and efficient method is introduced for the synthesis of 2-aryl-2,3-dihydroquinolin-4(1H)-ones under mild reaction conditions with improved yields by intramolecular cyclization of o-aminochalcones with zirconyl nitrate [Zn(O)(NO3)2·nH2O] as a water-tolerant Lewis-acid catalyst.

On the Mechanism of the Nickel-Catalyzed Boron Insertion into the C−O Bond of Benzofuran

2019 ◽  
Author(s):  
Ana Mateo-Martínez ◽  
Hayate Saito ◽  
Hideki Yorimitsu ◽  
Carles Bo
Keyword(s):  
Reductive Elimination ◽  
Nucleophilic Attack ◽  
Dft Studies ◽  
Reaction Conditions ◽  
Elementary Steps

<p>The reaction of benzofurans with diboron reagents and Cs<sub>2</sub>CO<sub>3</sub>catalyzed by Ni(0) complexes results in the insertion of boron into the C-O bond. The reaction conditions mimic those reported by Martin and Hosoya for borylating aryl C-F bonds, but neither the role of the base nor the sequence of elementary steps is clear. Herein we report on the mechanism of such transformation on the basis of DFT studies, which suggest that the base activates the diboron reagent and generates a reactive boryl group, that Ni(II) is reduced back to Ni(0) during the boryl insertion into the Ni-O bond, and that the classical reductive elimination step is best viewed as a ring-contracting nucleophilic attack. </p>

Molecular iodine as a mild catalyst for cross-coupling of alkenes and alcohols

2018 ◽  
Vol 90 (2) ◽  
pp. 377-386 ◽  
Author(s):  
Klara Čebular ◽  
Stojan Stavber
Keyword(s):  
Molecular Diversity ◽  
Bond Formation ◽  
Cross Coupling ◽  
Acid Catalyst ◽  
Molecular Iodine ◽  
Reaction Conditions ◽  
Benzyl Alcohols ◽  
Synthetic Procedure ◽  
Lewis Acid Catalyst ◽  
Solvent Free Reaction

Abstract C–C bond formation is one of the most fundamental approaches toward molecular diversity in organic synthesis. In pursuit of environmentally friendlier chemical approaches to organic chemistry, we present a new metal-free method for direct dehydrative cross-coupling of alcohols and alkenes using molecular iodine as a Lewis acid catalyst under solvent-free reaction conditions. The reaction is atom-economical, tolerant to air and allows simple synthetic procedure, furnishing Csp3–Csp2 coupling products with yields up to 97%. The method has proved efficient for coupling of secondary benzyl alcohols with phenyl-substituted alkenes.

Emerging Role of Green Oxidant I2/DMSO in Organic Synthesis

2018 ◽  
Vol 15 (6) ◽  
pp. 815-838 ◽  
Author(s):  
Pedavenkatagari Narayana Reddy ◽  
Basireddy V. Subba Reddy ◽  
Pannala Padmaja
Keyword(s):  
Organic Synthesis ◽  
Low Cost ◽  
Acid Catalyst ◽  
Sustainable Chemistry ◽  
Dmso System ◽  
Oxidative Transformations ◽  
Lewis Acid Catalyst ◽  
Catalyzed Reactions ◽  
Oxidative System

Background: I2/DMSO oxidative system catalyzed reactions have received considerable attention because they represent the advantages of being greener, efficient, atom-economical, low-cost, with mild conditions and ecofriendliness that meet with the requirements of sustainable chemistry. In recent times, the I2/DMSO oxidative system has been successfully applied in different types of organic reactions. Objective: The aim of this review is to highlight the synergistic effect of the combined use of iodine and DMSO in organic synthesis. Conclusion: It is clear from the review of the topic that a vast amount of work has been done in this area, employing an I2/DMSO system for diverse types of oxidative transformations as well as C-C and C-X bond formation reactions. In these reactions, iodine acts as a mild Lewis acid catalyst and DMSO servers as an oxidant, solvent and oxygen source. The role of iodine, DMSO as well as key intermediates involved in these reactions is discussed.

A Molecular Electron Density Theory Study of the Higher–Order Cycloaddition Reactions of Tropone with Electron-rich Ethylene. The Role of the Lewis Acid Catalyst in the Mechanism and Pseudocyclic Selectivity

2021 ◽  
Author(s):  
Luis R. Domingo ◽  
Patricia Perez
Keyword(s):  
Electron Density ◽  
Lewis Acid ◽  
Acid Catalyst ◽  
Higher Order ◽  
Cycloaddition Reactions ◽  
Molecular Electron ◽  
Lewis Acid Catalyst ◽  
Molecular Electron Density Theory

The higher–order cycloaddition reactions of tropone with nucleophilic ethylenes, in the absence and presence of Lewis acid (LA) catalysts, have been studied within Molecular Electron Density Theory (MEDT) at the...

scholarly journals Novel Role of Carbon Monoxide as a Lewis Acid Catalyst for Friedel-Crafts Reaction  [J. Am. Chem. Soc.2001,123, 8626−8627]. 

2002 ◽  
Vol 124 (7) ◽  
pp. 1553-1553
Author(s):  
Sensuke Ogoshi ◽  
Hiromitsu Nakashima ◽  
Kazumasa Shimonaka ◽  
Hideo Kurosawa
Keyword(s):  
Carbon Monoxide ◽  
Lewis Acid ◽  
Acid Catalyst ◽  
Lewis Acid Catalyst
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