Caveat in the stereochemical outcome of the organocatalytic Diels–Alder reaction in PEG-400

RSC Advances ◽  
2016 ◽  
Vol 6 (80) ◽  
pp. 76132-76136 ◽  
Author(s):  
Pantapalli M. Anitha ◽  
Prathama S. Mainkar ◽  
Shivakrishna Kallepu ◽  
V. S. Phani Babu ◽  
Cirandur Suresh Reddy ◽  
...  
Keyword(s):  
Alder Reaction ◽  
Diels Alder ◽  
Reaction Conditions ◽  
Peg 400 ◽  
Diels Alder Reaction

The organocatalytic Diels–Alder reaction in non-conventional solvent (PEG-400) has yielded cycloaddition products with diastereoselectivities hitherto not reported in detail using classical reaction conditions.

Single wall carbon nanotube (SWCNT)–gold nanorod (AuNR) conjugates via thermally-mild reaction conditions

2017 ◽  
Vol 41 (21) ◽  
pp. 12392-12396 ◽  
Author(s):  
Siting Ni ◽  
Jun Zhu ◽  
Mohamed Amine Mezour ◽  
R. Bruce Lennox
Keyword(s):  
Carbon Nanotube ◽  
Covalent Binding ◽  
Alder Reaction ◽  
Diels Alder ◽  
Gold Nanorod ◽  
Reaction Conditions ◽  
Single Wall Carbon ◽  
Inverse Electron Demand ◽  
Diels Alder Reaction ◽  
Electron Demand

A thermally-mild method for covalent binding of SWCNTs to AuNRs, based on an inverse-electron-demand Diels–Alder reaction, is established and discussed.

scholarly journals Direct Diels-Alder reaction of chitin derived 3-acetamido-5-acetylfuran

2022 ◽  
Author(s):  
Rafael Gomes ◽  
Juliana Pereira ◽  
João Ravasco ◽  
João Vale ◽  
Fausto Queda
Keyword(s):  
Alder Reaction ◽  
Diels Alder ◽  
Fine Tuning ◽  
Reduced Form ◽  
Partial Hydrolysis ◽  
Reaction Conditions ◽  
Diels Alder Reaction ◽  
Direct Use ◽  
Kinetics Of ◽  
Hydrolysis Of

The Diels-Alder (DA) reaction of biomass derived furans is an emerging technology for the preparation of new molecular entities and “drop-in” commodity chemicals. In this work we address the challenge of the direct use of electron-poor furanic platforms as dienes through the use of an unexplored chitin derived furan, 3-acetamido-5-acetylfuran (3A5AF). The 3-acetamido group promoted a remarkable increase in the kinetics of the DA allowing for the preparation of 7-oxanorbornenes (7-ONB) at 50 ºC. Partial hydrolysis of the enamide to hemi-acylaminals was possible upon fine tuning of the reaction conditions, disabling retro-DA processes. Finally, DA reaction of the reduced form of 3A5AF allowed quantitative formation of 7-ONB in aqueous condition after 10 minutes. Certanly these are the first steps for expanding the toolbox of chitin derived 3A5AF as diene.

COS-triggered Oxygen/Sulfur Exchange of Isatins: Chemoselective Synthesis of Functionalized Isoindigos and Spirothiopyrans via Self-condensation and Thio-Diels-Alder Reaction

2022 ◽  
Author(s):  
Wei Chen ◽  
Hui Zhou ◽  
Bai-Hao Ren ◽  
Wei-Min Ren ◽  
Xiaobing Lu
Keyword(s):  
Exchange Reaction ◽  
Sulfur Atom ◽  
Carbonyl Sulfide ◽  
Alder Reaction ◽  
Diels Alder ◽  
Reaction Conditions ◽  
Diels Alder Reaction ◽  
Chemoselective Synthesis ◽  
Sulfur Exchange

Herein, we present the first organocatalytic oxygen/sulfur atom exchange reaction (O/S ER) of isatins by employing carbonyl sulfide (COS) as novel sulfuring reagent under mild reaction conditions. 8-Diazabicyclo[5.4.0] undec-7-ene (DBU),...

scholarly journals Asymmetric Brønsted acid-catalyzed aza-Diels–Alder reaction of cyclic C-acylimines with cyclopentadiene

2012 ◽  
Vol 8 ◽  
pp. 1819-1824 ◽  
Author(s):  
Magnus Rueping ◽  
Sadiya Raja
Keyword(s):  
Alder Reaction ◽  
Optically Active ◽  
Diels Alder ◽  
Bronsted Acid ◽  
Brønsted Acid ◽  
Reaction Conditions ◽  
Diels Alder Reaction ◽  
Brönsted Acid ◽  
Acid Catalyzed ◽  
Chiral Bronsted Acid

A new chiral Brønsted acid-catalyzed aza-Diels–Alder reaction of cyclic C-acylimines with cyclopentadiene has been developed. The reaction provides optically active aza-tetracycles in good yields with high diastereo- and enantioselectivities under mild reaction conditions.

Thermal Routes to Substituted Cyclopentadienes

1972 ◽  
Vol 50 (19) ◽  
pp. 3186-3195 ◽  
Author(s):  
D. M. Findlay ◽  
Marie Lessard Roy ◽  
Stewart McLean
Keyword(s):  
Activation Energy ◽  
Low Temperature ◽  
Thermal Process ◽  
Kinetic Studies ◽  
Alder Reaction ◽  
Diels Alder ◽  
Reaction Conditions ◽  
Phenyl Azide ◽  
Aromatic Fragment ◽  
Diels Alder Reaction

An investigation has been made with the aim of finding a route to cyclopentadienes, particularly those with a single substituent at the 5-position, in which the final step is a thermal process of low enough activation energy that the cyclopentadiene produced does not undergo rearrangement by hydrogen migration under the reaction conditions. In the routes studied the final intermediates have been suitably substituted norbornenes which can lead to the required cyclopentadiene and an aromatic fragment by a retro-Diels–Alder reaction. In one series the intermediate was a phenyl azide adduct of norbornadiene which fragmented to cyclopentadiene and phenyltriazole, but the temperature required for this was clearly too high to allow substituted cyclopentadienes to be isolated before they had rearranged. In the course of this work, in addition to the exo-adduct of phenyl azide, the endo-adduct and a number of bisadducts were obtained and studied. In another series, adducts of tetraphenylcyclopentadienone and dimethyldiphenylcyclopentadienone with norbornadiene and 7-phenylnorbornadiene were prepared and studied. Decarbonylation of the adducts was effected both thermally and photochemically; in the latter case the reaction could be carried out at low temperature and the dihydrobenzene (a dihydrobenzonorbornadiene) produced was isolable. With or without isolation, the dihydrobenzene underwent a subsequent retro-Diels–Alder reaction to provide the cyclopentadiene and a substituted benzene. Kinetic studies showed that the activation energy for this process was almost but not quite low enough to satisfy the conditions stipulated, and in no case was a 5-substituted cyclopentadiene isolated before it had rearranged.

scholarly journals Aqueous Micellar Systems Formed by Surfactant Ionic Liquids. Application in Diels-Alder Reactions

Proceedings ◽  
2019 ◽  
Vol 41 (1) ◽  
pp. 72
Author(s):  
Jesica B. Soffietti ◽  
Claudia G. Adam ◽  
Claudia D. Della Rosa
Keyword(s):  
Ionic Liquids ◽  
Hydrocarbon Chain ◽  
Critical Micellar Concentration ◽  
Alder Reaction ◽  
Diels Alder ◽  
Reactive System ◽  
Reaction Conditions ◽  
Micellar Systems ◽  
Diels Alder Reaction ◽  
Micellar Effect

In the present work, our objective is to take advantage of the property presented by Ionic Liquids (ILs) based on 1-alkyl-3-methylimidazolium cations by having amphiphilic character when the alkyl group is a long hydrocarbon chain. These ILs can act as surfactants forming micelles in aqueous solution. In this sense, the micellar effect on a Diels-Alder reaction (DA) was analyzed taken as a reference. The reactive system studied consists of maleic anhydride and isoprene, variables such as diene:dienophile ratio and reaction temperatura among the most important were optimized. N,N-dodecylmethylimidazolium bromide was used at the critical micellar concentration (CMC) of 1 × 10−2 M. These “new systems” microheterogeneous would allow, in addition to better solubilization of non-polar substrates, to adopt milder reaction conditions.

Organocatayzed Oxa-Diels-Alder Reactions: Recent Progresses

Synthesis ◽  
2021 ◽  
Author(s):  
Anup Biswas ◽  
Samrat Kundu ◽  
Dhananjoy Pal ◽  
Amit Pal ◽  
Modhu Sudan Maji
Keyword(s):  
Alder Reaction ◽  
Diels Alder ◽  
Time Span ◽  
Reaction Conditions ◽  
Asymmetric Transformations ◽  
The Past ◽  
Diels Alder Reaction ◽  
Chiral Intermediates ◽  
Privileged Structure ◽  
Economical Process

Oxa-Diels-Alder reaction is a straightforward, atom-economical process for the construction of six membered oxa-cycle which is a privileged structure due to its omnipresence in several pharmaceuticals and natural products. Like many other asymmetric transformations, organocatalysis provides an elegant pathway to their synthesis via [4+2] annulation under mild reaction conditions. The oxa-Diels reactions either utilize α,β-unsaturated carbonyl as oxadiene with a suitable dienophile or simple carbonyl as dienophile with other dienes. A range of organocatalysts have been explored in the past decade to execute this strategy. The catalysts induce stereoselectivities via two basic reactivities: 1) Formation of chiral intermediates, 2) Selectively activating suitable reactants in transition state. The present review assembles organocatalyzed asymmetric oxa-Diels-Alder reactions published in last ten years’ time span with detailed discussion on mechanistic approaches.

Click synthesis by Diels-Alder reaction and characterisation of hydroxypropyl methylcellulose-based hydrogels

2014 ◽  
Vol 68 (10) ◽  
Author(s):  
Guo-Feng Wang ◽  
Hui-Juan Chu ◽  
Hong-Liang Wei ◽  
Xiao-Qian Liu ◽  
Zi-Xuan Zhao ◽  
...  
Keyword(s):  
Hydroxypropyl Methylcellulose ◽  
Gelation Time ◽  
Coupling Reaction ◽  
Alder Reaction ◽  
Diels Alder ◽  
Swelling Ratio ◽  
Reaction Conditions ◽  
Diels Alder Reaction ◽  
Increasing Temperature ◽  
Click Synthesis

AbstractThe Diels-Alder reaction was used to fabricate hydroxypropyl methylcellulose-based hydrogels. First, hydroxypropylmethylcellulose (HPMC) was modified by a carboxyl-containing diene molecule (SFA) which was synthesised from furfurylamine and succinic anhydride. Second, dienophile groups were introduced into HPMC by the coupling reaction with N-maleoyl alanine (AMI) using N,N′-dicyclohexylcarbodiimide (DCC) and 4-dimethylaminopyridine (DMAP). Subsequently, the asprepared furan- and maleimide-modified HPMC were dissolved in water and gelation was observed at a pre-determined temperature after a period of time. The samples thus obtained were characterised by FTIR, NMR, SEM, etc. The gelation time changing with temperature, concentration of the solution, and solvent was measured. It was found that gelation time decreased with increasing temperature and concentration of the solution, and that water had a rate-accelerating effect on Diels-Alder reaction. The swelling behaviour indicates that the hydrogels have a high swelling ratio in water and the swelling ratio increases with the increasing temperature. Taking into consideration that the HPMC-based hydrogels are prepared under mild reaction conditions with an adjustable gelation time and thermal stability, the method described here has a potential application in biomaterials, especially in the areas of tissue-engineering and drug-controlled release carriers.

Construction of bicyclic tetrahydroisoquinolinones by combination of an IMDAF-ring cleavage reaction of N-allyl-2-furan-2-yl-acetamides

2000 ◽  
Vol 78 (6) ◽  
pp. 749-756 ◽  
Author(s):  
Albert Padwa ◽  
Thomas S Reger
Keyword(s):  
Energy Difference ◽  
Alder Reaction ◽  
Diels Alder ◽  
Ring Cleavage ◽  
Am1 Calculations ◽  
Reaction Conditions ◽  
Intramolecular Cycloaddition ◽  
Tertiary Amide ◽  
Diels Alder Reaction ◽  
Semi Empirical

The intramolecular Diels-Alder reaction of furanyl amides derived from 2-furylacetic acid has been examined. Substrates containing either an imide or tertiary amide linkage between the furan and the dienophile underwent smooth cycloaddition upon thermolysis. By varying the reaction conditions, either the primary cycloadduct or the ring-opened and acetylated product could be isolated in excellent yield. The stereochemical outcome of the IMDAF cycloaddition has the side arm of the tethered alkenyl group oriented syn with respect to the oxygen bridge. Semi-empirical AM1 calculations show that the exo-cycloadduct is 11 kcal lower in energy than the corresponding endo adduct and, presumably, some of this energy difference is reflected in the transition state for the cycloaddition. The IMDAF reaction of N-allyl-[2-(3,4-dimethoxyphenethyl)]-2-furanyl-2-yl-acetamide proceeded in 90% yield upon heating in xylene. The 4+2-cycloadduct undergoes ring-opening on treatment with base and the resulting alcohol was converted into the corresponding benzyl ether. Raney nickel reduction followed by Bischler-Napieralski cyclization furnished the tetracyclic skeleton of the berberine alkaloids.Key words: intramolecular, cycloaddition, Diels-Alder, furanylamide, heterocycle.

ChemInform Abstract: Caveat in the Stereochemical Outcome of the Organocatalytic Diels-Alder Reaction in PEG-400.

ChemInform ◽  
2016 ◽  
Vol 47 (52) ◽  
Author(s):  
Pantapalli M. Anitha ◽  
Prathama S. Mainkar ◽  
Shivakrishna Kallepu ◽  
V. S. Phani Babu ◽  
Cirandur Suresh Reddy ◽  
...  
Keyword(s):  
Alder Reaction ◽  
Diels Alder ◽  
Peg 400 ◽  
Diels Alder Reaction
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