Geminal bis(silane)-controlled regio- and stereoselective oxidative Heck reaction of enol ethers with terminal alkenes to give push–pull 1,3-dienes

2015 ◽  
Vol 51 (85) ◽  
pp. 15546-15549 ◽  
Author(s):  
Linjie Li ◽  
Yang Chu ◽  
Lu Gao ◽  
Zhenlei Song
Keyword(s):  
Heck Reaction ◽  
Enol Ethers ◽  
Reaction Proceeds ◽  
Terminal Alkenes

A geminal bis(silane)-controlled regio- and stereoselective oxidative Heck reaction of enol ethers with terminal alkenes has been developed. The reaction proceeds with α,β-coupling regioselectivity to give push–pull Z,E-1,3-dienes in good yields.

scholarly journals Radical Chain Monoalkylation of Pyridines

2021 ◽  
Author(s):  
Samuel Rieder ◽  
Camilo Meléndez ◽  
Kleni Mulliri ◽  
Philippe Renaud
Keyword(s):  
Rate Constant ◽  
Iodine Atom ◽  
Radical Chain ◽  
Enol Ethers ◽  
Alkyl Radicals ◽  
Reaction Proceeds ◽  
Order Of Magnitude ◽  
Enol Esters ◽  
The One ◽  
Neutral Conditions

<p>The monoalkylation of N-methoxypyridinium salts with alkyl radicals generated from alkenes (via hydroboration with catecholborane), alkyl iodides (via iodine atom transfer) and xanthates is reported. The reaction proceeds under neutral conditions since no acid is needed to activate the heterocycle and does not require the use of an external oxidant. A rate constant for the addition of a primary radical to N-methoxylepidinium >107 M–1 s–1 was experimentally determined. This rate constant is more than one order of magnitude larger than the one measured for the addition of primary alkyl radical to protonated lepidine demonstrating the remarkable reactivity of methoxypyridinium salts towards radicals. The reaction could be extended to a three component carbopyridinylation of electron rich alkenes including enol esters, enol ethers and enamides.</p>

Aliphatic Radical Relay Heck Reaction at Unactivated C(sp3)–H Sites of Alcohols

2018 ◽  
Author(s):  
Padon Chuentragool ◽  
Dongari Yadagiri ◽  
Taiki Morita ◽  
Sumon Sarkar ◽  
Marvin Parasram ◽  
...  
Keyword(s):  
Visible Light ◽  
Heck Reaction ◽  
Room Temperature ◽  
Halogen Atom ◽  
Organic Molecules ◽  
Alkyl Halides ◽  
Aliphatic Alcohols ◽  
Aliphatic Radical ◽  
Reaction Proceeds

<div>The Mizoroki−Heck reaction is one of the most efficient methods for alkenylation of</div><div>aryl, vinyl, and alkyl halides. Due to its innate nature, this protocol requires the employment of compounds possessing a halogen atom at the site of functionalization. However, the accessibility of organic molecules possessing a halogen atom at a particular site in aliphatic systems is extremely limited. Thus, a protocol that would allow a Heck reaction to occur at a specific non-functionalized C(sp3)−H site would be highly desirable.</div><div>Here, we report a radical relay Heck reaction which allows for a selective remote</div>alkenylation of aliphatic alcohols at unactivated β-, γ- and δ-C(sp3 20 )–H sites. The use of easily installable/removable Si-based auxiliary enables selective I-atom/radical translocation events at remote C−H sites followed by the Heck reaction. Notably, the reaction proceeds smoothly under mild visible light-mediated conditions at room temperature, producing highly modifiable and valuable alkenol products from readily available alcohols feedstocks. <br>

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 Organoboron Mediated Homolytic Aromatic Substitution of N-Methoxypyridinium Salts

2021 ◽  
Author(s):  
Samuel Rieder ◽  
Camilo Meléndez ◽  
Kleni Mulliri ◽  
Philippe Renaud
Keyword(s):  
Rate Constant ◽  
Aromatic Substitution ◽  
Enol Ethers ◽  
Alkyl Radicals ◽  
Homolytic Aromatic Substitution ◽  
Reaction Proceeds ◽  
Order Of Magnitude ◽  
Enol Esters ◽  
The One ◽  
Neutral Conditions

<p>The monoalkylation of N-methoxypyridinium salts with alkyl radicals generated from alkenes (via hydroboration with catecholborane), alkyl iodides (via iodine atom transfer) and xanthates is reported. The reaction proceeds under neutral conditions since no acid is needed to activate the heterocycle and does not require the use of an external oxidant. A rate constant for the addition of a primary radical to N-methoxylepidinium >107 M–1 s–1 was experimentally determined. This rate constant is more than one order of magnitude larger than the one measured for the addition of primary alkyl radical to protonated lepidine demonstrating the remarkable reactivity of methoxypyridinium salts towards radicals. The reaction could be extended to a three component carbopyridinylation of electron rich alkenes including enol esters, enol ethers and enamides.</p>

scholarly journals A Giese Reaction for Electron-Rich Alkenes

2020 ◽  
Author(s):  
Qi Huang ◽  
Sankar Rao Suravarapu ◽  
Philippe Renaud
Keyword(s):  
Hydrogen Atom ◽  
Room Temperature ◽  
Chain Transfer ◽  
Chain Process ◽  
Enol Ethers ◽  
Silyl Enol Ethers ◽  
Terminal Alkenes ◽  
Enol Esters ◽  
A Chain ◽  
General Method

A general method for the hydroalkylation of electron-rich terminal and non-terminal alkenes such as enol esters, alkenyl sulfides, enol ethers, silyl enol ethers, enamides and enecarbamates has been developed. The reactions are carried out at room temperature under air initiation in the presence of triethylborane acting as a chain transfer reagent and 4-<i>tert</i>-butylcatechol (TBC) as a source of hydrogen atom. The efficacy of the reaction is best explained by very favorable polar effects supporting the chain process and minimizing undesired polar reactions. The stereoselective hydroalkylation of chiral <i>N</i>-(alk-1-en-1-yl)oxazolidin-2-ones takes place with good to excellent diastereocontrol.

The Mizoroki–Heck Reaction Initiated Formal C(sp3)-H Arylation of Carbonyl Compounds

2021 ◽  
Author(s):  
Nan-Quan Jiang ◽  
Hai-Yan Li ◽  
Zhong-Jian Cai ◽  
Shun-Jun Ji
Keyword(s):  
Heck Reaction ◽  
Carbonyl Compounds ◽  
Reaction Proceeds

Herein, we present a Mizoroki–Heck reaction initiated formal C(sp3)-H arylation of α-methylcinnamaldehydes. The reaction proceeds smoothly under phosphane-free conditions, and provides a facile method to access important α-methylcinnamaldehyde derivatives with...

Cross dehydrogenative coupling of sugar enol ethers with terminal alkenes in the synthesis of pseudo-disaccharides, chiral oxadecalins and a conjugated triene

2018 ◽  
Vol 16 (15) ◽  
pp. 2666-2677 ◽  
Author(s):  
Nazar Hussain ◽  
Madhu Babu Tatina ◽  
Debaraj Mukherjee
Keyword(s):  
Enol Ethers ◽  
Efficient Strategy ◽  
Dehydrogenative Coupling ◽  
Terminal Alkenes ◽  
Conjugated Triene

An efficient strategy for the synthesis of C-2 and C-3 branched sugar dienes via cross dehydrogenative coupling of sugar enol ethers with terminal alkenes was developed.

Efficient Synthesis of Chromones with Alkenyl Functionalities by the Heck Reaction

2010 ◽  
Vol 63 (11) ◽  
pp. 1582 ◽  
Author(s):  
Tamás Patonay ◽  
Attila Vasas ◽  
Attila Kiss-Szikszai ◽  
Artur M. S. Silva ◽  
José A. S. Cavaleiro
Keyword(s):  
Heck Reaction ◽  
Halogen Atom ◽  
Phase Transfer ◽  
Bromine Atom ◽  
Tetrabutylammonium Bromide ◽  
Phase Transfer Catalyst ◽  
Efficient Synthesis ◽  
Terminal Alkenes

The usefulness of the Heck reaction in the field of chromones has been demonstrated. Bromochromones with the halogen atom in their rings A and B were reacted with various terminal alkenes to give hitherto unknown alkenyl‐substituted chromones. Reactivity of the substrates was found to markedly depend on the position of the bromine atom. Under phosphine‐free conditions using a phase‐transfer catalyst additive (tetrabutylammonium bromide), shorter reaction periods and usually higher yields were obtained.

scholarly journals Organoboron Mediated Homolytic Aromatic Substitution of N-Methoxypyridinium Salts

2021 ◽  
Author(s):  
Samuel Rieder ◽  
Camilo Meléndez ◽  
Kleni Mulliri ◽  
Philippe Renaud
Keyword(s):  
Rate Constant ◽  
Aromatic Substitution ◽  
Enol Ethers ◽  
Alkyl Radicals ◽  
Homolytic Aromatic Substitution ◽  
Reaction Proceeds ◽  
Order Of Magnitude ◽  
Enol Esters ◽  
The One ◽  
Neutral Conditions

<p>The monoalkylation of N-methoxypyridinium salts with alkyl radicals generated from alkenes (via hydroboration with catecholborane), alkyl iodides (via iodine atom transfer) and xanthates is reported. The reaction proceeds under neutral conditions since no acid is needed to activate the heterocycle and does not require the use of an external oxidant. A rate constant for the addition of a primary radical to N-methoxylepidinium >107 M–1 s–1 was experimentally determined. This rate constant is more than one order of magnitude larger than the one measured for the addition of primary alkyl radical to protonated lepidine demonstrating the remarkable reactivity of methoxypyridinium salts towards radicals. The reaction could be extended to a three component carbopyridinylation of electron rich alkenes including enol esters, enol ethers and enamides.</p>

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