Mechanistic studies on initial C–C bond formation in the zeolite ZSM-5 catalysed methanol conversion reaction: evidence against a radical pathway

1987 ◽  
pp. 843-844 ◽  
Author(s):  
Roger Hunter ◽  
Graham J. Hutchings ◽  
Wolfgang Pickl
Keyword(s):  
Bond Formation ◽  
Methanol Conversion ◽  
Mechanistic Studies ◽  
Conversion Reaction

Design and Development of Fe-Catalyzed Intra- and Intermolecular Carbofunctionalization of Vinyl Cyclopropanes

2019 ◽  
Author(s):  
Lei Liu ◽  
Wes Lee ◽  
Mingbin Yuan ◽  
Chris Acha ◽  
Michael B. Geherty ◽  
...  
Keyword(s):  
Bond Formation ◽  
Cross Coupling ◽  
Alkyl Halides ◽  
Grignard Reagents ◽  
Mechanistic Studies ◽  
Radical Intermediates ◽  
Design And Implementation ◽  
Solvent Cage ◽  
Radical Cascade ◽  
Radical Processes

Design and implementation of the first (asymmetric) Fe-catalyzed intra- and intermolecular difunctionalization of vinyl cyclopropanes (VCPs) with alkyl halides and aryl Grignard reagents has been realized via a mechanistically driven approach. Mechanistic studies support the diffusion of the alkyl radical intermediates out of the solvent cage to participate in an intra- or -intermolecular radical cascade with the VCP followed by re-entering the Fe radical cross-coupling cycle to undergo selective C(sp2)-C(sp3) bond formation. Overall, we provide new design principles for Fe-mediated radical processes and underscore the potential of using combined computations and experiments to accelerate the development of challenging transformations.

scholarly journals Mechanistic studies on the N-alkylation of amines with alcohols catalysed by iridium(i) complexes with functionalised N-heterocyclic carbene ligands

2018 ◽  
Vol 8 (9) ◽  
pp. 2381-2393 ◽  
Author(s):  
M. Victoria Jiménez ◽  
Javier Fernández-Tornos ◽  
Miguel González-Lainez ◽  
Beatriz Sánchez-Page ◽  
F. Javier Modrego ◽  
...  
Keyword(s):  
Bond Formation ◽  
Theoretical Studies ◽  
Mechanistic Studies ◽  
Carbene Ligands ◽  
Experimental And Theoretical Studies

Experimental and theoretical studies give support for an iridium-catalyzed C–N bond formation.

I2/TBHP-Promoted Approach to α-Keto Esters from Trifluoromethyl β-Diketones and Alcohols via C–C Bond Cleavage

Synlett ◽  
2017 ◽  
Vol 28 (15) ◽  
pp. 2018-2023 ◽  
Author(s):  
Xiang Fang ◽  
Xueyan Yang ◽  
Tongle Shao ◽  
Jun Zhou ◽  
Chen Jin ◽  
...  
Keyword(s):  
Oxidative Coupling ◽  
Bond Cleavage ◽  
Bond Formation ◽  
Coupling Reaction ◽  
Mechanistic Studies ◽  
Metal Free ◽  
Oxidation Pathway ◽  
Keto Esters ◽  
Oxidative Coupling Reaction

A metal-free oxidative coupling reaction of trifluoromethyl β-diketones with alcohols for the synthesis of α-keto esters in good to excellent yields has been developed. Preliminary mechanistic studies suggest that an I2/TBHP promoted sequential iodination, C–C bond cleavage, C–O bond formation and oxidation pathway is involved in this reaction.

Photoinduced Oxidative Cross-Coupling for O–S Bond Formation: A Facile Synthesis of Alkyl Benzenesulfonates

Synlett ◽  
2017 ◽  
Vol 28 (13) ◽  
pp. 1558-1563 ◽  
Author(s):  
Aiwen Lei ◽  
Atul Singh ◽  
Hong Yi ◽  
Guoting Zhang ◽  
Changliang Bian ◽  
...  
Keyword(s):  
Visible Light ◽  
Bond Formation ◽  
Cross Coupling ◽  
Selective Synthesis ◽  
Mechanistic Studies ◽  
Facile Synthesis ◽  
Metal Free

We have developed a photoinduced oxidative cross-coupling of thiophenols with alcohols for O–S bond formation. The protocol uses visible light, a metal-free photocatalyst, and oxygen as the oxidant for the selective synthesis of alkyl benzenesulfonates; no ligand co-additive is necessary. Mechanistic studies suggested that the disulfide and alkyl benzenesulfinate are involved as intermediates and that the transformation proceeds by a radical pathway.

scholarly journals Efficient Copper Catalyzed Multi-component Synthesis of N-acyl amidines via Acyl Nitrenes

2019 ◽  
Author(s):  
K.M. van Vliet ◽  
Lara H. Polak ◽  
Maxime A. Siegler ◽  
J.I. van der Vlugt ◽  
Célia Fonseca Guerra ◽  
...  
Keyword(s):  
Direct Synthesis ◽  
Bond Formation ◽  
Organometallic Complexes ◽  
Biologically Active ◽  
Mechanistic Studies ◽  
Copper Acetylide ◽  
Substrate Conversion ◽  
Cu Catalyst ◽  
New Type ◽  
Synthetic Routes

Direct synthetic routes to amidines are desired, as they are widely present in many biologically active compounds and organometallic complexes. N-Acyl amidines in particular can be used as a starting material for the synthesis of heterocycles and have several other applications. Here, we describe a fast and practical copper catalyzed 3-component reaction of aryl acetylenes, amines and easily accessible 1,4,2-dioxazol-5-ones to N-acyl amidines, generating CO<sub>2</sub> as the only by-product. Transformation of the dioxazolones on the Cu-catalyst generates acyl nitrenes that rapidly insert into the copper acetylide Cu-C bond rather than undergoing an undesired Curtius rearrangement. For non-aromatic dioxazolones, [Cu(OAc)(Xantphos)] is a superior catalyst for this transformation, leading to full substrate conversion within 10 minutes. For the direct synthesis of N-benzoyl amidine derivatives from aromatic dioxazolones, [Cu(OAc)(Xantphos)] proved to be inactive, but moderate to good yields were obtained when using simple CuI as the catalyst. Mechanistic studies revealed the aerobic instability of one of the intermediates at low catalyst loadings, but the reaction could still be performed in air for most substrates when using catalyst loadings of 5 mol%. The herein reported procedure does not only provide a new, practical and direct route to N-acyl amidines, but also represents a new type of<br>C-N bond formation.

scholarly journals Catalytic Benzolactamization Through Isonitrile Insertion Enabled 1,4-Palladium Shift

2021 ◽  
Author(s):  
Fulin Zhang ◽  
Ruihua Zhao ◽  
Lei Zhu ◽  
Yinghua Yu ◽  
Saihu Liao ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Heterocyclic Compounds ◽  
Bond Activation ◽  
Bond Formation ◽  
Bioactive Molecules ◽  
Mechanistic Studies ◽  
Carbon And Nitrogen ◽  
New Methods ◽  
Novel Approach ◽  
Bicyclic System

<b>Isoindolinone is a class of versatile <i>N</i>-heterocycles embedded in many bioactive molecules and natural products. The invention of new methods to synthesize these heterocyclic compounds with easily accessible chemicals is always attractive. Herein, a conceptually novel approach to access this bicyclic system via isonitrile insertion enabled 1,4-pallaidum shift is described. Compared with conventional isonitrile participated C-H bond activation, both carbon and nitrogen atoms in isonitrile moiety are engaged in new bond formation. Notably, two different isoindolinones can be obtained selectively by switching the bases employed. Mechanistic studies including DFT calculations have shed lights on the reaction mechanism and explained the selectivity led to different products. Moreover, the power of current benzolactamization is further demonstrated by providing concise routes to key intermediates of indoprofen, indobufen, aristolactams, lennoxamine and falipamil.</b>

scholarly journals Photoinduced Deaminative Borylation of Unactivated Aromatic Amines Enhanced by CO2

2021 ◽  
Author(s):  
Akira Shiozuka ◽  
Kohei Sekine ◽  
Yoichiro Kuninobu
Keyword(s):  
Aromatic Amines ◽  
Bond Cleavage ◽  
Bond Formation ◽  
Inhibitory Effect ◽  
Light Irradiation ◽  
Mechanistic Studies ◽  
Reaction Conditions ◽  
Metal Free ◽  
Stoichiometric Amount ◽  
Optimal Reaction

Herein, direct unactivated C-N borylation of aromatic amines by a photocatalyst was achieved under mild and metal-free conditions. The C-N borylation of aromatic amines with bis(pinacolato)diboron (B<sub>2</sub>pin<sub>2</sub>) proceeded in the presence of a pyrene catalyst under light irradiation (λ = 365 nm) <a>to afford desired borylated products</a> and aminoborane as a byproduct. The yield of borylated product improved under a CO<sub>2</sub> atmosphere. Reactions conducted in the presence of a stoichiometric amount of aminoborane under N<sub>2</sub> or CO<sub>2</sub> indicated that CO<sub>2</sub> reduced the inhibitory effect of aminoborane. Optimal reaction conditions were applied to a variety of aromatic amines. Mechanistic studies suggested that the C-N bond cleavage and C-B bond formation proceeded via a concerted pathway.

Rhodium(I)-Catalysed Aryl C–H Carboxylation of 2-Arylanilines with CO2

2019 ◽  
Author(s):  
yuzhen gao ◽  
Zhihua Cai ◽  
Shangda Li ◽  
Gang Li
Keyword(s):  
General Type ◽  
Bond Cleavage ◽  
Bond Formation ◽  
Direct Conversion ◽  
Activation Process ◽  
Amino Group ◽  
Mechanistic Studies ◽  
Organometallic Reagent ◽  
Cleavage Step ◽  
Neutral Conditions

<b>An unprecedented amino-group assisted C–H carboxylation of 2-arylanilines with CO<sub>2</sub> under redox-neutral conditions using a Rhodium(I)-catalyst has been developed. This reaction was promoted by a phosphine ligand with <i>t</i>-BuOK as the base and did not require the use of an extra strong organometallic reagent. Notably, this protocol may involve an oxidative addition in the C–H bond cleavage step and is distinct from previous Rh(I) or Rh(II)-catalysed methods for C–H carboxylation with </b><b>CO<sub>2</sub> </b><b>mechanistically. It enabled an efficient direct conversion of a broad range of 2-(hetero)arylanilines including electron-deficient heteroarenes to various phenanthridinones, which could be further transformed to other synthetically useful compounds readily. Preliminary mechanistic studies were carried out and possible intermediates of the reaction were evaluated, which revealed that the Rh(I)-catalyst is essential for the C–H activation process, providing a promising general type of method for utilization of </b><b>CO<sub>2</sub></b><b> for C–C bond formation.</b><br>

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