scholarly journals 1H NMR Analysis of the Metathesis Reaction between 1-Hexene and (E)-Anethole Using Grubbs 2nd Generation Catalyst: Effect of Reaction Conditions on (E)-1-(4-Methoxyphenyl)-1-hexene Formation and Decomposition

Catalysts ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1483
Author(s):  
Marthinus Rudi Swart ◽  
Charlene Marais ◽  
Elizabeth Erasmus
Keyword(s):  
1H Nmr ◽  
Maximum Concentration ◽  
Metathesis Reaction ◽  
Reaction Conditions ◽  
2Nd Generation ◽  
Cross Metathesis ◽  
First Order Kinetics ◽  
Different Temperatures ◽  
The Cross ◽  
Catalyst Effect

The metathesis of 1-hexene and (E)-anethole in the presence of Grubbs 2nd generation catalyst was monitored by in situ 1H NMR spectroscopy at different temperatures (15 °C, 25 °C, and 45 °C) and anethole mol fractions (XAnethole ≈ 0.17, 0.29, 0.5, 0.71, 0.83). Time traces confirmed the instantaneous formation of (E)-1-(4-methoxyphenyl)-1-hexene, the cross-metathesis product. A maximum concentration of (E)-1-(4-methoxyphenyl)-1-hexene is reached fairly fast (the time depending on the reaction conditions), and this is followed by a decrease in the concentration of (E)-1-(4-methoxyphenyl)-1-hexene due to secondary metathesis. The maximum concentration of (E)-1-(4-methoxyphenyl)-1-hexene was more dependent on the XAnethole than the temperature. The highest TOF (3.46 min−1) was obtained for the reaction where XAnethole was 0.16 at 45 °C. The highest concentration of the cross-metathesis product was however achieved after 6 min with an anethole mol fraction of 0.84 at 25 °C. A preliminary kinetic study indicated that the secondary metathesis reaction followed first order kinetics.

Complete Stereocontrol in the Synthesis of Harmonine and Novel Analogues Facilitated by a Grubbs Z-Selective Cross-Metathesis Catalyst

2015 ◽  
Vol 68 (12) ◽  
pp. 1815 ◽  
Author(s):  
Steven-Alan G. Abel ◽  
Wesley J. Olivier ◽  
Richard L. Pederson ◽  
Alex C. Bissember ◽  
Jason A. Smith
Keyword(s):  
The Self ◽  
Metathesis Reaction ◽  
Cross Metathesis ◽  
Metathesis Catalyst ◽  
The Cross

(R)-Harmonine was synthesised in 15 % overall yield via a six-step sequence exploiting a Z-selective cross-metathesis reaction as its centrepiece. By this strategy, the cis-olefin present in the target could be installed exclusively. The use of an alcohol and an ester as the amine precursors was crucial for isolating the cross-metathesis product from the self-metathesis products. This method was also used to prepare two novel analogues of harmonine.

Kinetics and Mechanism of Oxidation of Aliphatic Secondary Alcohols by Benzimidazolium Fluorochromate in Dimethyl Sulphoxide Solvent

2021 ◽  
Vol 37 (3) ◽  
pp. 626-633
Author(s):  
Bhawana Arora ◽  
Jitendra Ojha ◽  
Pallavi Mishra
Keyword(s):  
Activation Parameters ◽  
Sigmatropic Rearrangement ◽  
Dimethyl Sulphoxide ◽  
Secondary Alcohols ◽  
Hydrogen Ions ◽  
Reaction Conditions ◽  
First Order Kinetics ◽  
Aqueous Solvent ◽  
Ester Formation ◽  
Different Temperatures

Oxidation of secondary alcohols is an important part of synthetic organic chemistry. Various studies are carried out at different reaction conditions to determine the best mechanistic pathways. In our study, oxidation of different secondary alcohols was done by using Benzimidazolium Fluorochromate in Dimethyl Sulphoxide, which is a non-aqueous solvent. Oxidation resulted in the formation of ketonic compounds. The reaction showed first order kinetics both in BIFC and in the alcohols. Hydrogen ions were used to catalyze the reaction. We selected four different temperatures to carry out our study. The correlation within the activation parameters like enthalpies and entropies was in accordance with the Exnerʼs criterion. The deuterated benzhydrol (PhCDOHPh) oxidation exhibited an important primary kinetic isotopic effect (kH / kD = 5.76) at 298 K. The solvent effect was studied using the multiparametric equations of Taft and Swain. There was no effect of addition of acrylonitrile on the oxidation rate. The mechanism involved sigmatropic rearrangement with the transfer of hydrogen ion taking place from alcohol to the oxidant via a cyclic chromate ester formation.

Regulation of the degree of blockiness of the norbornene–cyclooctene copolymer synthesized via the cross-metathesis reaction

2016 ◽  
Vol 58 (3) ◽  
pp. 292-297 ◽  
Author(s):  
Yu. I. Denisova ◽  
M. L. Gringolts ◽  
L. B. Krentsel’ ◽  
G. A. Shandryuk ◽  
A. D. Litmanovich ◽  
...  
Keyword(s):  
Metathesis Reaction ◽  
Cross Metathesis ◽  
The Cross

scholarly journals Cross-metathesis reaction of α- and β-vinyl C-glycosides with alkenes

2015 ◽  
Vol 11 ◽  
pp. 1392-1397 ◽  
Author(s):  
Ivan Šnajdr ◽  
Kamil Parkan ◽  
Filip Hessler ◽  
Martin Kotora
Keyword(s):  
Metathesis Reaction ◽  
Simple Method ◽  
Cross Metathesis ◽  
Terminal Alkenes ◽  
The Cross

Cross-metathesis of α- and β-vinyl C-deoxyribosides and α-vinyl C-galactoside with various terminal alkenes under different conditions was studied. The cross-metathesis of the former proceeded with good yields of the corresponding products in ClCH2CH2Cl the latter required the presence of CuI in CH2Cl2 to achieve good yields of the products. A simple method for the preparation of α- and β-vinyl C-deoxyribosides was also developed. In addition, feasibility of deprotection and further transformations were briefly explored.

Ruthenium-catalyzed cross-metathesis with electron-rich phenyl vinyl sulfide enables access to 2,3-dideoxy-d-ribopyranose ring system donors

RSC Advances ◽  
2014 ◽  
Vol 4 (38) ◽  
pp. 19794-19799 ◽  
Author(s):  
Omar Boutureira ◽  
M. Isabel Matheu ◽  
Yolanda Díaz ◽  
Sergio Castillón
Keyword(s):  
Microwave Irradiation ◽  
Ring System ◽  
Metathesis Reaction ◽  
Vinyl Sulfide ◽  
Cross Metathesis ◽  
The Cross ◽  
Flexible Metal ◽  
Phenyl Vinyl

Microwave irradiation effectively accelerates the cross-metathesis reaction of 2-deoxy-d-ribose hydroxyalkene and derivatives with electron-rich phenyl vinyl sulfide using commercially available ruthenium-based catalysts, thus providing a flexible metal-mediated route to 2,3-dideoxy-d-ribopyranose ring system donors.

scholarly journals The cross-metathesis of methyl oleate with cis-2-butene-1,4-diyl diacetate and the influence of protecting groups

2011 ◽  
Vol 7 ◽  
pp. 1-8 ◽  
Author(s):  
Arno Behr ◽  
Jessica Pérez Gomes
Keyword(s):  
Methyl Oleate ◽  
Renewable Resources ◽  
Value Added ◽  
Ruthenium Catalysts ◽  
Protecting Groups ◽  
Catalyst Loading ◽  
Reaction Conditions ◽  
Functional Monomers ◽  
Cross Metathesis ◽  
The Cross

Background: α,ω-Difunctional substrates are useful intermediates for polymer synthesis. An attractive, sustainable and selective (but as yet unused) method in the chemical industry is the oleochemical cross-metathesis with preferably symmetric functionalised substrates. The current study explores the cross-metathesis of methyl oleate (1) with cis-2-butene-1,4-diyl diacetate (2) starting from renewable resources and quite inexpensive base chemicals. Results: This cross-metathesis reaction was carried out with several phosphine and N-heterocyclic carbene ruthenium catalysts. The reaction conditions were optimised for high conversions in combination with high cross-metathesis selectivity. The influence of protecting groups present in the substrates on the necessary catalyst loading was also investigated. Conclusions: The value-added methyl 11-acetoxyundec-9-enoate (3) and undec-2-enyl acetate (4) are accessed with nearly quantitative oleochemical conversions and high cross-metathesis selectivity under mild reaction conditions. These two cross-metathesis products can be potentially used as functional monomers for diverse sustainable polymers.

Study of the Cross-Metathesis Reaction of α-Hydroxy β,γ-Unsaturated Amides towards a Rapid and Flexible Total ­Synthesis of Symbioramide and its Isomer

Synlett ◽  
2017 ◽  
Vol 29 (02) ◽  
pp. 230-234 ◽  
Author(s):  
Alexandre Gratais ◽  
Samir Bouzbouz
Keyword(s):  
Methyl Ester ◽  
Total Synthesis ◽  
Metathesis Reaction ◽  
Cross Metathesis ◽  
Metathesis Reactions ◽  
The Cross

The reactivity of novel α-hydroxy β,γ-unsaturated amides in cross-metathesis reactions was extensively studied and used to perform a short total synthesis of symbioramide and its isomer from ­l-serine methyl ester.

Synthesis of Unsaturated Esters by Cross-Metathesis of Terpenes and Natural Rubber Using Ru-Alkylidene Catalysts

2019 ◽  
Vol 23 (12) ◽  
pp. 1356-1364
Author(s):  
Araceli Martínez ◽  
Mikhail A. Tlenkopatchev ◽  
Selena Gutiérrez ◽  
Manuel Burelo ◽  
Joel Vargas ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Unsaturated Ester ◽  
Low Molecular Weight ◽  
Diethyl Maleate ◽  
Metathesis Reaction ◽  
Unsaturated Esters ◽  
Cross Metathesis ◽  
Dimethyl Maleate ◽  
The Cross ◽  
Low Activity

This study reports the cross-metathesis of bicyclic β-pinene, acyclic cis-3- methylpent-2-ene terpenes and the natural rubber with functionalized olefins, a route for the functionalization of the carbon-carbon double bond of natural products to obtain aliphatic unsaturated esters. The production of unsaturated esters from β-pinene and cis-3- methylpent-2-ene via cross-metathesis reaction with dimethyl maleate and diethyl maleate in the presence of the ruthenium-alkylidene [Ru(Cl)2(=CHPh)(1,3-bis(2,4,6- trimethylphenyl)-2-imidazolidinylidene)(PCy3)] (I), [Ru(Cl)2(=CH(o-isopropoxyphenylmethylene))( 1,3-bis(2,4,6-trimethylphenyl) -2-imidazolidinylidene)] (II) and rutheniumvinylidene [RuCl2(=C=CH(p-C6H4CF3))(PCy3)2] (III) was carried out. Results showed that the reaction of β-pinene with diethyl maleate using II catalyst produced unsaturated esters with 43 % selectivity. I and III catalysts showed low activity toward the cross-metathesis of β-pinene and dimethyl maleate. A survey about the cross-metathesis of acyclic cis-3-methylpent-2-ene with diethyl maleate by II catalyst was also studied. The formation of ethyl but-2-enoate and ethyl-3-methylpent-2-enoate products was highly selective by 63 %. The unsaturated esters formation from the cross-metathesis degradation of natural rubber (99.9 % cis-polyisoprene) with dimethyl maleate and diethyl maleate using I-III catalysts was accomplished as well. I and II catalysts showed high activity in the degradation of natural rubber with diethyl maleate to produce the low molecular weight of oligomers unsaturated ester products (Mn = 1 x 103 g mol-1) with isoprene units of m = 10 – 27 and yields ranging from 68 to 94 %.

scholarly journals Fishing for the right catalyst for the cross-metathesis reaction of methyl oleate with 2-methyl-2-butene

2017 ◽  
Vol 7 (6) ◽  
pp. 1284-1296 ◽  
Author(s):  
A. Sytniczuk ◽  
A. Kajetanowicz ◽  
K. Grela
Keyword(s):  
Methyl Oleate ◽  
Metathesis Reaction ◽  
Cross Metathesis ◽  
The Cross ◽  
The Right

A comparison of the reactivity of different ruthenium-based complexes in the cross-metathesis reaction of methyl oleate was presented.

Exploiting the cross-metathesis reaction in the synthesis of pseudo-oligosaccharides

2009 ◽  
Vol 7 (12) ◽  
pp. 2635 ◽  
Author(s):  
Paolo Ronchi ◽  
Stefano Vignando ◽  
Sara Guglieri ◽  
Laura Polito ◽  
Luigi Lay
Keyword(s):  
Metathesis Reaction ◽  
Cross Metathesis ◽  
The Cross
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