New Regio- and Stereocontrolles Reactions of 2-Vinylindoles with CC-Dienophiles: Diels-Alder Reactions, Ene Reactions and Michael Additions

Heterocycles ◽  
1988 ◽  
Vol 27 (10) ◽  
pp. 2353 ◽  
Author(s):  
Ulf Pindur ◽  
Manfred Eitel
Keyword(s):  
Diels Alder ◽  
Ene Reactions ◽  
Michael Additions

scholarly journals Rheometer Evidences for the Co-Curing Effect of a Bismaleimide in Conjunction with the Accelerated Sulfur on Natural Rubber/Chloroprene Rubber Blends

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1510
Author(s):  
Marek Pöschl ◽  
Shibulal Gopi Sathi ◽  
Radek Stoček ◽  
Ondřej Kratina
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Tensile Properties ◽  
Crosslinking Agent ◽  
Alder Reaction ◽  
Diels Alder ◽  
Ene Reactions ◽  
Rubber Blends ◽  
Diels Alder Reaction ◽  
Chloroprene Rubber

The rheometer curing curves of neat natural rubber (NR) and neat chloroprene rubber (CR) with maleide F (MF) exhibit considerable crosslinking torque at 180 °C. This indicates that MF can crosslink both these rubbers via Alder-ene reactions. Based on this knowledge, MF has been introduced as a co-crosslinking agent for a 50/50 blend of NR and CR in conjunction with accelerated sulfur. The delta (Δ) torque obtained from the curing curves of a blend with the addition of 1 phr MF was around 62% higher than those without MF. As the content of MF increased to 3 phr, the Δ torque was further raised to 236%. Moreover, the mechanical properties, particularly the tensile strength of the blend with the addition of 1 phr MF in conjunction with the accelerated sulfur, was around 201% higher than the blend without MF. The overall tensile properties of the blends cured with MF were almost retained even after ageing the samples at 70 °C for 72 h. This significant improvement in the curing torque and the tensile properties of the blends indicates that MF can co-crosslink between NR and CR via the Diels–Alder reaction.

ChemInform Abstract: Generation and Trapping of 5,6-Dimethylenepyrimidin-4-ones in Diels- Alder and Michael Additions.

ChemInform ◽  
2010 ◽  
Vol 27 (20) ◽  
pp. no-no
Author(s):  
A. C. TOME ◽  
J. A. S. CAVALEIRO ◽  
R. C. STORR
Keyword(s):  
Diels Alder ◽  
Michael Additions

ChemInform Abstract: Tandem Diels-Alder and Retro-Ene Reactions of 1-Sulfenyl- and 1-Sulfonyl-1,3-dienes as a Traceless Route to Cyclohexenes.

ChemInform ◽  
2015 ◽  
Vol 46 (7) ◽  
pp. no-no
Author(s):  
Jin Choi ◽  
Hoyoon Park ◽  
Hyun Jung Yoo ◽  
Sinae Kim ◽  
Erik J. Sorensen ◽  
...  
Keyword(s):  
Diels Alder ◽  
Ene Reactions

scholarly journals Zur Reaktivität des Germaethens Me2Ge=C(SiMe3)2: Mechanistische Aspekte der Diels-Aider- und En-Reaktionen [1] / On the Reactivity of Germaethene Me2Ge=C (SiMe3)2: Mechanistic Aspects of Diels Alder and Ene Reactions [1]

1996 ◽  
Vol 51 (6) ◽  
pp. 838-850 ◽  
Author(s):  
Nils Wiberg ◽  
Susanne Wagner
Keyword(s):  
Double Bond ◽  
Energy Difference ◽  
Diels Alder ◽  
Bond Polarity ◽  
Ene Reactions ◽  
Ene Reaction

Abstract Diels-Alder and ene reactions of germaethene Me2Ge=C(SiMe3)2 (2) with butadienes respectively, take place regioselectively, as well as stereoselectively. They are accelerated by an increasing tendency of substituents in butadiene or propene to donate electrons (e.g. 2-methylbutadiene > butadiene; 2-methylpropene > propene), and retarded by an increasing bulkyness of substituents in 1,4- or 1,3-positions (e.g. 1-methylbutadiene > 2-methylbutadiene; 1-vinylpropene > propene). It is concluded from these studies that Diels-Alder and ene reactions of 2 occur - like those of Me2Si=C(SiMe3)2 (1) or of ethenes >C=C< - in a concerted way and are HOMOdiene-LUMOdienophile and HOMOene-LUMOenophile controlled. Thus 2 and 1 behave as carbon analogues. With regard to a specific diene or ene (e.g. anthracene; toluene), 2 is the better dienophile or enophile than 1 or ethenes. With a fixed diene/ene mixture (e.g. butadiene/propene), 2 acts as the better dienophile, while 1 is the better enophile. These results can be explained by the π/π*- energy difference and the double bond polarity decreasing in the direction 1 > 2. Only cis-piperylene gives a [2+2] cycloadduct with 2. besides two [4+2] cycloadducts, and an ene reaction product

ChemInform Abstract: Diels-Alder- and Ene-Reactions of 2-Azaallenium Salts.

ChemInform ◽  
2010 ◽  
Vol 25 (17) ◽  
pp. no-no
Author(s):  
A. GEISLER ◽  
E.-U. WUERTHWEIN
Keyword(s):  
Diels Alder ◽  
Ene Reactions
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