Cobalt-Catalyzed Highly Diastereoselective [3+2] Carboannulation Reaction: Facile Access to Substituted Indane Derivatives

2022 ◽  
Author(s):  
Chandra Volla ◽  
Arnab Dey ◽  
Anurag Singh
Keyword(s):  
Aerobic Conditions ◽  
Reaction Proceeds ◽  
Earth Abundant ◽  
Directing Group

An efficient oxidative [3+2] annulation reaction of aryl hydrazones and heterobicyclic alkenes has been realized with inexpensive and earth-abundant cobalt-salts under aerobic conditions. The reaction proceeds via directing-group assisted C-H...

Intermolecular C–H Amidation of Alkenes with Carbon Monoxide and Azides via Tandem Palladium Catalysis

Synthesis ◽  
2021 ◽  
Author(s):  
Zheng-Yang Gu ◽  
Yang Wu ◽  
Feng Jin ◽  
Bao Xiaoguang ◽  
Ji-Bao Xia
Keyword(s):  
Carbon Monoxide ◽  
Palladium Catalysis ◽  
Computational Studies ◽  
Organic Azides ◽  
Reaction Proceeds ◽  
Palladium Catalyzed ◽  
Directing Group ◽  
And Control

An atom- and step-economic intermolecular multi-component palladium-catalyzed C–H amidation of alkenes with carbon monoxide and organic azides has been developed for the synthesis of alkenyl amides. The reaction proceeds efficiently without an ortho-directing group on the alkene substrates. Nontoxic dinitrogen is generated as the sole by-product. Computational studies and control experiments have revealed that the reaction takes place via an unexpected mechanism by tandem palladium catalysis.

scholarly journals Palladium-Catalysed C–F Alumination of Fluorobenzenes: Mechanistic Diversity and Origin of Selectivity

2020 ◽  
Author(s):  
Feriel Rekhroukh ◽  
Wenyi Chen ◽  
Ryan Brown ◽  
Andrew J. P. White ◽  
Mark Crimmin
Keyword(s):  
Dft Calculations ◽  
Bond Activation ◽  
Oxidative Addition ◽  
Fluorine Content ◽  
Model Potential ◽  
Heterometallic Complex ◽  
Experimental Support ◽  
Highly Active ◽  
Reaction Proceeds ◽  
Directing Group

A palladium pre-catalyst, [Pd(PCy<sub>3</sub>)<sub>2</sub>] is reported for the efficient and selective C–F alumination of fluorobenzenes with the aluminium(I) reagent [{(ArNCMe)<sub>2</sub>CH}Al] (<b>1</b>, Ar = 2,6-di-iso-propylphenyl). The catalytic protocol results in the transformation of sp<sup>2</sup> C–F bonds to sp<sup>2</sup> C–Al bonds and provides a route into reactive organoaluminium complexes (<b>2a-h</b>) from fluorocarbons. The catalyst is highly active. Reactions proceed within 5 minutes at 25 ºC (and at appreciable rates at even –50 ºC) and the scope includes low-fluorine-content substrates such as fluorobenzene, difluorobenzenes and trifluorobenzenes. The reaction proceeds with complete chemoselectivity (C–F vs C–H) and high regioselectivities ( >90% for C–F bonds adjacent to the most acidic C–H sites). The heterometallic complex [Pd(PCy<sub>3</sub>)(<b>1</b>)<sub>2</sub>] was shown to be catalytically competent. Catalytic C–F alumination proceeds with a KIE of 1.1–1.3. DFT calculations have been used to model potential mechanisms for C–F bond activation. These calculations suggest that two competing mechanisms may be in operation. Pathway 1 involves a ligand-assisted oxidative addition to [Pd(<b>1</b>)<sub>2</sub>] and leads directly to the product. Pathway 2 involves a stepwise C–H to C–F functionalisation mechanism in which the C–H bond is broken and reformed along the reaction coordinate, allowing it to act as a directing group for the adjacent C–F site. This second mechanism explains the experimentally observed regioselectivity. Experimental support for this C–H activation playing a key role in C–F alumination was obtained by employing [{(MesNCMe)<sub>2</sub>CH}AlH<sub>2</sub>] (<b>3</b>, Mes = 2,4,6-trimethylphenyl) as a reagent in place of 1. In this instance, the kinetic C–H alumination intermediate could be isolated. Under catalytic conditions this intermediate converts to the thermodynamic C–F alumination product.

scholarly journals Photoinduced Copper-Catalyzed Asymmetric C-O Cross-Coupling

2021 ◽  
Author(s):  
Jun Chen ◽  
Yu-Jie Liang ◽  
Peng-Zi Wang ◽  
Guo-Qing Li ◽  
Bin Zhang ◽  
...  
Keyword(s):  
Room Temperature ◽  
Cross Coupling ◽  
Asymmetric Induction ◽  
Light Emitting ◽  
Bond Forming ◽  
Redox Active ◽  
Reaction Proceeds ◽  
Earth Abundant ◽  
Radical Generation ◽  
Allylic Esters

<b>Whereas considerable advances have recently been achieved in radical-involved catalytic asymmetric C-N bond formation, there has been little progress in the corresponding C-O bond-forming processes. Here we describe a photoinduced copper-catalyzed cross-coupling of readily oxime esters and 1,3-dienes to generate diversely substituted allylic esters with high regio- and enantioselectivity (>75 examples; up to 95% ee). The reaction proceeds at room temperature under excitation by purple light-emitting diodes and features the use of a single, earth-abundant copper-based chiral catalyst as both the photoredox catalyst for radical generation and the source of asymmetric induction in C-O coupling. Combined experimental and DFT computational studies suggest the formation of π-allylcopper complex from redox-active oxime esters as bifunctional reagents and 1,3-dienes through a radical-polar crossover process.</b>

scholarly journals Palladium-Catalysed C–F Alumination of Fluorobenzenes: Mechanistic Diversity and Origin of Selectivity

2020 ◽  
Author(s):  
Feriel Rekhroukh ◽  
Wenyi Chen ◽  
Ryan Brown ◽  
Andrew J. P. White ◽  
Mark Crimmin
Keyword(s):  
Dft Calculations ◽  
Bond Activation ◽  
Oxidative Addition ◽  
Fluorine Content ◽  
Model Potential ◽  
Heterometallic Complex ◽  
Experimental Support ◽  
Highly Active ◽  
Reaction Proceeds ◽  
Directing Group

A palladium pre-catalyst, [Pd(PCy<sub>3</sub>)<sub>2</sub>] is reported for the efficient and selective C–F alumination of fluorobenzenes with the aluminium(I) reagent [{(ArNCMe)<sub>2</sub>CH}Al] (<b>1</b>, Ar = 2,6-di-iso-propylphenyl). The catalytic protocol results in the transformation of sp<sup>2</sup> C–F bonds to sp<sup>2</sup> C–Al bonds and provides a route into reactive organoaluminium complexes (<b>2a-h</b>) from fluorocarbons. The catalyst is highly active. Reactions proceed within 5 minutes at 25 ºC (and at appreciable rates at even –50 ºC) and the scope includes low-fluorine-content substrates such as fluorobenzene, difluorobenzenes and trifluorobenzenes. The reaction proceeds with complete chemoselectivity (C–F vs C–H) and high regioselectivities ( >90% for C–F bonds adjacent to the most acidic C–H sites). The heterometallic complex [Pd(PCy<sub>3</sub>)(<b>1</b>)<sub>2</sub>] was shown to be catalytically competent. Catalytic C–F alumination proceeds with a KIE of 1.1–1.3. DFT calculations have been used to model potential mechanisms for C–F bond activation. These calculations suggest that two competing mechanisms may be in operation. Pathway 1 involves a ligand-assisted oxidative addition to [Pd(<b>1</b>)<sub>2</sub>] and leads directly to the product. Pathway 2 involves a stepwise C–H to C–F functionalisation mechanism in which the C–H bond is broken and reformed along the reaction coordinate, allowing it to act as a directing group for the adjacent C–F site. This second mechanism explains the experimentally observed regioselectivity. Experimental support for this C–H activation playing a key role in C–F alumination was obtained by employing [{(MesNCMe)<sub>2</sub>CH}AlH<sub>2</sub>] (<b>3</b>, Mes = 2,4,6-trimethylphenyl) as a reagent in place of 1. In this instance, the kinetic C–H alumination intermediate could be isolated. Under catalytic conditions this intermediate converts to the thermodynamic C–F alumination product.

scholarly journals 1,2,3-Triazole amine as directing group in promoting catalytic oxidative C–H olefination under aerobic conditions

Tetrahedron ◽  
2016 ◽  
Vol 72 (22) ◽  
pp. 2756-2762 ◽  
Author(s):  
Xiaohan Ye ◽  
Yanwei Zhang ◽  
Ying He ◽  
Xiaodong Shi
Keyword(s):  
Aerobic Conditions ◽  
Directing Group

Rhodium(III)-Catalyzed C–H Activation/Alkylation of Diazabicyclic Olefins with Aryl Ketones: Facile Synthesis of Functionalized Cyclopentenes

Synlett ◽  
2018 ◽  
Vol 29 (15) ◽  
pp. 2023-2026 ◽  
Author(s):  
K. Radhakrishnan ◽  
P. Santhini ◽  
Greeshma Gopalan ◽  
A. Smrithy
Keyword(s):  
Ammonium Acetate ◽  
Bond Activation ◽  
Facile Synthesis ◽  
Reaction Proceeds ◽  
Aryl Ketones ◽  
Directing Group ◽  
Aryl Ketone

A facile synthesis of biologically important trans-functionalized cyclopentenes by a mild Rh(III)-catalyzed alkylation of strained ­diazabicyclic olefins with aryl ketones in the presence of ammonium ­acetate has been developed. The reaction proceeds through C–H bond activation of the aryl ketone groups by transforming them in to an ­autocleavable directing group, such as in situ-formed imine.

scholarly journals Manganese Catalysed Dehydrogenative Synthesis of Urea Derivatives and Polyureas

2021 ◽  
Author(s):  
Aniekan Owen ◽  
Annika Preiss ◽  
Angus McLuskie ◽  
Chang Gao ◽  
Gavin Peters ◽  
...  
Keyword(s):  
Pharmaceutical Drugs ◽  
Urea Derivatives ◽  
Coupling Process ◽  
Dehydrogenative Coupling ◽  
Pincer Complex ◽  
Reaction Proceeds ◽  
Earth Abundant ◽  
Broad Variety ◽  
Resin Precursors ◽  
A Current

Urea derivatives are prevalent intermediates in the synthesis of resin precursors, dyes, agrochemicals, and pharmaceutical drugs. Furthermore, polyureas are useful plastics with applications in coating, adhesive, and biomedical industries and have a current annual market of USD 885 million. However, the conventional methods for the synthesis of urea derivatives and polyureas involve toxic reagents such as (di)isocyanates, phosgene, CO, and azides. We present here the synthesis of (poly)ureas using much less toxic reagents - (di)amines, and methanol via a catalytic dehydrogenative coupling process. The reaction is catalyzed by a pincer complex of an earth-abundant metal, manganese, and liberates H2 gas, valuable by itself, as the only by-product making the overall process atom-economic, and sustainable. A broad variety of symmetrical, and unsymmetrical urea derivatives and polyureas have been synthesized in moderate to quantitative yields using this catalytic protocol. Mechanistic insights have also been provided using experiments and DFT computation suggesting that the reaction proceeds via an isocyanate intermediate.

scholarly journals Photoinduced Copper-Catalyzed Asymmetric C-O Cross-Coupling

2021 ◽  
Author(s):  
Jun Chen ◽  
Yu-Jie Liang ◽  
Peng-Zi Wang ◽  
Guo-Qing Li ◽  
Bin Zhang ◽  
...  
Keyword(s):  
Room Temperature ◽  
Cross Coupling ◽  
Asymmetric Induction ◽  
Light Emitting ◽  
Bond Forming ◽  
Redox Active ◽  
Reaction Proceeds ◽  
Earth Abundant ◽  
Radical Generation ◽  
Allylic Esters

<b>Whereas considerable advances have recently been achieved in radical-involved catalytic asymmetric C-N bond formation, there has been little progress in the corresponding C-O bond-forming processes. Here we describe a photoinduced copper-catalyzed cross-coupling of readily oxime esters and 1,3-dienes to generate diversely substituted allylic esters with high regio- and enantioselectivity (>75 examples; up to 95% ee). The reaction proceeds at room temperature under excitation by purple light-emitting diodes and features the use of a single, earth-abundant copper-based chiral catalyst as both the photoredox catalyst for radical generation and the source of asymmetric induction in C-O coupling. Combined experimental and DFT computational studies suggest the formation of π-allylcopper complex from redox-active oxime esters as bifunctional reagents and 1,3-dienes through a radical-polar crossover process.</b>

Synthesis of 3-Oxoisoindoline-1-carboxamides through Sequential Four-Component Ugi Reaction/Oxidative Nucleophilic Substitution of Hydrogen

Synlett ◽  
2020 ◽  
Vol 31 (09) ◽  
pp. 861-865
Author(s):  
Saeed Balalaie ◽  
Ahmed Al-Harrasi ◽  
Kamran Amiri ◽  
Muhammad U. Anwar
Keyword(s):  
Nucleophilic Substitution ◽  
Aerobic Oxidation ◽  
Ugi Reaction ◽  
Nucleophilic Substitution Of Hydrogen ◽  
Reaction Conditions ◽  
Bond Forming ◽  
Reaction Proceeds ◽  
Forming Efficiency ◽  
High Bond ◽  
Directing Group

This paper describes a diversity-oriented approach to the formation of 3-oxoisoindoline-1-carboxamide derivatives utilizing the potential of the nitro group as a directing group. The reaction proceeds through a novel class of post-transformation reactions through a sequential four-component Ugi reaction/oxidative nucleophilic substitution of hydrogen. The 3-oxoisoindoline-1-carboxamide derivatives were synthesized in the presence of a base under mild reaction conditions with high regio- and chemoselectivity. The aerobic oxidation, high bond-forming efficiency, high atom economy, and good to excellent yields are the main advantages of this approach.

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