Radical Metal-Free Borylation of Aryl Iodides

Synthesis ◽  
2017 ◽  
Vol 49 (21) ◽  
pp. 4759-4768 ◽  
Author(s):  
Sandra Pinet ◽  
Mathieu Pucheault ◽  
Virginie Liautard ◽  
Mégane Debiais
Keyword(s):  
Steric Hindrance ◽  
Radical Mechanism ◽  
Electronic Effects ◽  
Simple Metal ◽  
Reaction Conditions ◽  
Metal Free ◽  
Aryl Iodides ◽  
Reaction Proceeds ◽  
Electronic Effects Of Substituents

A simple metal-free borylation of aryl iodides mediated by a fluoride sp2–sp3 diboron adduct is described. The reaction conditions are compatible with various functional groups. Electronic effects of substituents do not affect the borylation while steric hindrance does. The reaction proceeds via a radical mechanism in which pyridine serves to stabilize the boryl radicals, generated in situ.

Metal-Free Oxidative C(sp3)–N Coupling by HBr and DMSO: A Novel Synthesis of 2,3-Dihydroquinazolin-4(1H)-ones

Synlett ◽  
2018 ◽  
Vol 29 (07) ◽  
pp. 912-917 ◽  
Author(s):  
Parviz Ranjbar ◽  
Narjes Rezaei ◽  
Ehsan Sheikhi
Keyword(s):  
Oxidative Cyclization ◽  
Cyclization Reaction ◽  
Primary Amines ◽  
Isatoic Anhydride ◽  
Reaction Conditions ◽  
Coupling Process ◽  
Benzylic Alcohols ◽  
Metal Free ◽  
Novel Synthesis

A metal-free oxidative C(sp3)–N coupling process has been developed for the synthesis of 2,3-dihydroquinazolin-4(1H)-ones. The reaction between primary amines, isatoic anhydride, and benzylic alcohols in the presence of HBr in DMSO at 80 °C affords 2,3-dihydroquinazolin-4(1H)-ones in excellent yields. Under these reaction conditions, benzylic alcohols react with in situ generated bromodimethylsulfonium bromide to form alkoxysulfonium intermediates. These intermediates undergo an oxidative cyclization reaction with primary amines and isatoic anhydride to produce the title products.

A chiral Brønsted acid-catalyzed highly enantioselective Mannich-type reaction of α-diazo esters with in situ generated N-acyl ketimines

2018 ◽  
Vol 54 (28) ◽  
pp. 3516-3519 ◽  
Author(s):  
Rajshekhar A. Unhale ◽  
Milon M. Sadhu ◽  
Sumit K. Ray ◽  
Rayhan G. Biswas ◽  
Vinod K. Singh
Keyword(s):  
Phosphoric Acid ◽  
Reaction Conditions ◽  
Type Reaction ◽  
Chiral Phosphoric Acid ◽  
Brönsted Acid ◽  
Diazo Esters ◽  
Reaction Proceeds ◽  
Acid Catalyzed ◽  
Chiral Bronsted Acid

A chiral phosphoric acid-catalyzed asymmetric Mannich-type reaction of α-diazo esters with in situ generated N-acyl ketimines, derived from 3-aryl-3-hydroxyisoindolinones has been demonstrated. The reaction proceeds smoothly under mild reaction conditions.

scholarly journals Selective Nitration of Chlorobenzene by NO2 in the Alkali Zeolite NaZSM-5

2013 ◽  
Vol 2013 ◽  
pp. 1-5
Author(s):  
Scott J. Kirkby
Keyword(s):  
Gas Phase ◽  
Room Temperature ◽  
Temperature Dependent ◽  
Reaction Conditions ◽  
Cation Site ◽  
Zeolite Lattice ◽  
Reaction Proceeds ◽  
Ft Ir ◽  
Electron Donation

Chlorobenzene was reacted with NO2, in the initially acid-free zeolite NaZSM-5, to yield para-chloronitrobenzene exclusively. The precursors were loaded sequentially into self-supporting pellets of the zeolite, contained within a stainless steel cell, from the gas phase. The reaction proceeds spontaneously at room temperature. It is, however, very temperature dependent and effectively ceases at zero degrees Celsius. The reaction was monitored in situ using FT-IR. The active nitrating agent is formed from the partial electron donation by the NO2 to the Na+ cations present in the zeolite lattice. Under the reaction conditions, chlorobenzene is not readily mobile through the pore system; thus, only the molecules adsorbed near a cation site react to form para-chloronitrobenzene.

scholarly journals Efficient pyrazole moiety-containing ligands for Cu-catalyzed O-arylation of phenols

2019 ◽  
Author(s):  
Yingying Zhao ◽  
Xiangyong Wang ◽  
Ryo Kaneyama ◽  
Koichi Kodama ◽  
Takuji Hirose
Keyword(s):  
Steric Hindrance ◽  
Binding Sites ◽  
Coupling Reaction ◽  
Aryl Halides ◽  
Catalyst Loading ◽  
Radical Mechanism ◽  
Coupling Reactions ◽  
Electronic Effects ◽  
Electronic Nature ◽  
Imine Nitrogen

Seven N2- and N3-ligands (L1–L7) were developed for the ligand-assisted CuI-catalyzed coupling reactions of aryl halides with phenols. The structural and electronic effects were studied for various combinations of pyridine and/or imine nitrogen binding sites in the ligands. 2-(1-Pyrazolyl)pyridine (L1) featuring two types of binding sites gave the best results, with yields of up to 90% at 100 °C at a catalyst loading of 10 mol% (CuI/L in 1:1 ratio). A non-radical mechanism, proposed for the L1-promoted coupling reaction, well explained the different effects of electronic nature of the substituent and steric hindrance on phenols and aryl halides.

Catalytic Sulfone Upgrading Reaction with Alcohols via Ru(II)

2019 ◽  
Author(s):  
Tomas Vojkovsky ◽  
Shubham Deolka ◽  
Saiyyna P. Stepanova ◽  
Michael C. Roy ◽  
Eugene Khaskin
Keyword(s):  
Functional Groups ◽  
Secondary Alcohol ◽  
Value Added ◽  
Catalytic Dehydrogenation ◽  
Reaction Conditions ◽  
Stoichiometric Amount ◽  
Reaction Proceeds ◽  
One Step ◽  
Value Added Products

<a>Sulfones and sulfonamides with an α-CH bond can be easily alkylated by aliphatic alcohols to add the carbon skeleton of the alcohol via a one-step, Ru(II) catalyzed redox neutral reaction. The reaction requires a sub-stoichiometric amount of base and produces only water as a byproduct. A number of pharmaceutically relevant functional groups such as piperidine, morpholine, etc. are well tolerated under the reaction conditions to give higher value-added products in one step from widely available substrates. The reaction proceeds through a sulfone carbanion addition to an in-situ generated aldehyde formed via catalytic dehydrogenation and subsequent catalyst mediated replacement of the secondary alcohol by hydrogen.</a>

scholarly journals One-Pot NBS-Promoted Synthesis of Imidazoles and Thiazoles from Ethylarenes in Water

Molecules ◽  
2019 ◽  
Vol 24 (5) ◽  
pp. 893 ◽  
Author(s):  
Liang Chen ◽  
Huajian Zhu ◽  
Jiang Wang ◽  
Hong Liu
Keyword(s):  
One Pot ◽  
Metal Free ◽  
Reaction Proceeds ◽  
In Situ Formation

A facile and eco-friendly method has been developed for the synthesis of imidazoles and thiazoles from ethylarenes in water. The reaction proceeds via in situ formation of α-bromoketone using NBS as a bromine source as well as an oxidant, followed by trapping with suitable nucleophiles to provide the corresponding products in good yields under metal-free conditions.

scholarly journals Direct C–H Alpha Arylation of Enones with ArI(O2CR)2 Reagents

2019 ◽  
Author(s):  
Felipe Cesar Sousa e Silva ◽  
Nguyen T Van ◽  
Sarah Wengryniuk
Keyword(s):  
Claisen Rearrangement ◽  
Bond Formation ◽  
Hypervalent Iodine ◽  
Enol Ethers ◽  
Silyl Enol Ethers ◽  
Metal Free ◽  
Wide Range ◽  
Reaction Proceeds ◽  
Mechanistic Investigations

Herein, we report the metal-free direct C–H arylation of enones mediated by hypervalent iodine reagents. The reaction proceeds via a reductive iodonium Claisen rearrangement of <i>in situ </i>b-pyridinium silyl enol ethers. The aryl groups are derived from ArI(O<sub>2</sub>CCF<sub>3</sub>)<sub>2</sub> reagents, which are readily accessed from the parent iodoarenes. It is tolerant of a wide range of substitution patterns and the incorporated arenes maintain the valuable iodine functional handle. Mechanistic investigations implicate arylation via an umpoled “enolonium” species and that the presence of a b-pyridinium moiety is critical for desired C–C bond formation.

scholarly journals Metal-Free Photoredox Phosphonation of C–N and C–X Bonds in Aqueous Solvent Mixtures

2021 ◽  
Author(s):  
Lei Pan ◽  
Alexandra Kelley ◽  
Maria Victoria Cooke ◽  
Macy Deckert ◽  
Sébastien Laulhé
Keyword(s):  
Building Blocks ◽  
Solvent Mixture ◽  
Solvent Mixtures ◽  
Environmental Footprint ◽  
Reaction Conditions ◽  
Metal Free ◽  
Aqueous Solvent ◽  
Wide Range ◽  
Reaction Proceeds ◽  
Phosphonate Esters

Aryl phosphonate esters are valuable moieties for the pharmaceutical and agrochemical industries. Accessing such compounds from affordable and abundant phosphite reagents and a wide range of aromatic building blocks under metal-free, visible light-induced reaction conditions would represent a desirable technology. Herein, we present an efficient and mild methodology for the synthesis of aromatic phosphonate esters in good to excellent yields using DBU and phenothiazine as a photoredox catalyst. The reaction exhibits wide functional group compatibility enabling the transformation in presence of ketone, amide, ester, amine, and alcohol moieties. Importantly, the reaction proceeds using a green solvent mixture primarily composed of water, thus lowering the environmental footprint of this transformation compared to current methods.

scholarly journals Aromatic heterocycles XII. Semiempirical PM3 study of Diels-Alder cycloaddition reaction of substituted phosphabenzenes

2004 ◽  
Vol 2 (1) ◽  
pp. 34-51
Author(s):  
Liliana Pacureanu ◽  
Mircea Mracec ◽  
Zeno Simon
Keyword(s):  
Steric Hindrance ◽  
Reasonable Agreement ◽  
Cycloaddition Reaction ◽  
Diels Alder ◽  
Electronic Effects ◽  
Reaction Energy ◽  
Aromatic Heterocycles ◽  
Electronic Effects Of Substituents

AbstractWe report the results of a semiempirical PM3 study of the 1,4 cycloaddition reaction of substituted λ3-phosphabenzenes with alkynes. The influence of the nature, position and steric hindrance of substituents on the reaction energy is studied. Except for some values, the results are in reasonable agreement with experimental observations and electronic effects of substituents.

Catalytic Sulfone Upgrading Reaction with Alcohols via Ru(II)

2019 ◽  
Author(s):  
Tomas Vojkovsky ◽  
Shubham Deolka ◽  
Saiyyna P. Stepanova ◽  
Michael C. Roy ◽  
Eugene Khaskin
Keyword(s):  
Functional Groups ◽  
Secondary Alcohol ◽  
Value Added ◽  
Catalytic Dehydrogenation ◽  
Reaction Conditions ◽  
Stoichiometric Amount ◽  
Reaction Proceeds ◽  
One Step ◽  
Value Added Products

<a>Sulfones and sulfonamides with an α-CH bond can be easily alkylated by aliphatic alcohols to add the carbon skeleton of the alcohol via a one-step, Ru(II) catalyzed redox neutral reaction. The reaction requires a sub-stoichiometric amount of base and produces only water as a byproduct. A number of pharmaceutically relevant functional groups such as piperidine, morpholine, etc. are well tolerated under the reaction conditions to give higher value-added products in one step from widely available substrates. The reaction proceeds through a sulfone carbanion addition to an in-situ generated aldehyde formed via catalytic dehydrogenation and subsequent catalyst mediated replacement of the secondary alcohol by hydrogen.</a>

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