Diels-Alder reaction

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	Diels-Alder reaction - Wikipedia, the free encyclopedia
		The Diels-Alder reaction is an organic chemical reaction (specifically, a cycloaddition) between a conjugated diene and a substituted alkene, commonly termed the dienophile to form a substituted cyclohexene system.
		Otto Paul Hermann Diels and Kurt Alder were awarded the Nobel Prize in Chemistry in 1950 for their work on this reaction.
		The Diels-Alder reaction is generally considered the "Mona Lisa" of reactions in organic chemistry since it requires very little energy to create the very useful six-membered ring.
	en.wikipedia.org /wiki/Diels-Alder_reaction (2050 words)

	Diels-Alder Reaction
		The Diels- Alder Reaction of Cyclopentadiene with Maleic Anhydride
	www.chem.umr.edu /web/Subjects/Organic/Experiments/exp8.html (9 words)

	Diels-Alder Reaction
		The mechanism of the Diels-Alder reaction is usually shown using a cyclic flow of electrons between the diene and the dienophile.
		The Diels-Alder reaction forms two new carbon-carbon single bonds which in the product connect carbon 1 and carbon 4 of the diene to the two carbons in the double bond (or triple bond) of the dienophile (shown in red in the following structures).
		Remember that in the starting materials there were double bonds between carbons 1 and 2 and between carbons 3 and 4 of the conjugated diene, and a(nother) π-bond between the two carbons of the dienophile.
	www.rocky.edu /~barbaroj/diels-alder/diels-alder.html (477 words)

	Diels-Alder Reaction
		There are “inverse demand” Diels Alder Reactions that involve the overlap of the HOMO of the dienophile with the unoccupied MO of the diene.
		Strong Counteranion Effects on the Catalytic Activity of Cationic Silicon Lewis Acids in Mukaiyama Aldol and Diels-Alder Reactions
		A Mild and Efficient Asymmetric Hetero-Diels-Alder Reaction of the Brassard Diene with Aldehydes
	www.organic-chemistry.org /namedreactions/diels-alder-reaction.shtm (353 words)

	Diels - Alder reaction
		This is a concerted reaction that involves a cyclic flow of electrons.
		Such a process is called a pericyclic reaction.
	www.fsj.ualberta.ca /chimie/chem161/bALLYL/sld027.htm (20 words)

	Diels Alder Reaction
		The Diels-Alder reaction is second only to the Aldol condensation in importance for organic chemistry.
		He and Diels wrote their first paper on the reaction of dienes with quinones in 1928.
		Alder was a professor of chemistry at Kiel from 1934 to 1936.
	users.ox.ac.uk /~mwalter/web_05/resources/name_reactions/diels_alder.shtml (360 words)

	Diels Alder Reaction - EMOC
		Stereoselectivity is observed for the Diels Alder reaction.
		The rate of the Diels Alder reaction is facilitated by having electron-releasing substituents on one reactant (usually the diene) and electron-withdrawing substituents on the other reactant (usually the dienophile).
		The Diels Alder reaction is a unique reaction of dienes with either alkenes or alkynes, which are referred to as dienophiles.
	www.chem.memphis.edu /parrill/EMOC/roadmap/da.html (231 words)

	Diastereoselective effects of the Diels-Alder Reaction
		Crucial to the synthesis and a method of inducing the stereochemistry into the ring-A, is the Diels-Alder reaction, discovered by this manner in the Stoodley group, Manchester, U.K. The D-glucose based diene (as type 1 or 2), a modiefied Danishefsky’s diene used the
		In order to undergo a Diels-Alder reaction, the s-cis geometry of the diene must exist, as shown for (2) in the scheme above.
		‘Frontier Orbitals and Organic Chemical Reactions’, I. Fleming, p.
	www.jonathanpmiller.com /anomeric (500 words)

	Diels-Alder Reaction Basics
		In the Diels-Alder reaction written in the forward direction as above, there is a loss of 3 pi bonds and a gain of one new pi bond and two new sigma bonds.
		The Diels-Alder reaction is a simultaneous movement of 6 electrons, breaking 3 bonds and forming 3 new bonds.
		For a discussion of this stereoselectivity, click on over to the Diels-Alder Reaction Stereochemistry page.
	academics.keene.edu /rblatchly/OrgoCommon/hand/conjdiene/DAReactionBasics.html (147 words)

	Diels Alder Exp
		Swirl the solution in the ice bath for a few minutes until the exothermic reaction is over and the Diels-Alder adduct separates as a white solid.
		When dicyclopentadiene is distilled, it undergoes a reverse Diels-Alder reaction yielding two molar equivalents of cyclopentadiene.
		Once the reaction is complete, heat the resulting mixture on a hot plate until the solid completely dissolves (in the case that moisture has gotten into the system, a little of the corresponding diacid may remain undissolved as this point and should be removed by filtration of the hot solution).
	www.bradley.edu /las/chm/Course/351/Diels-Alder.htm (387 words)

	Lewis Acid Catalysis of a Diels-Alder Reaction in Water
		Relative to the uncatalyzed reaction in acetonitrile, catalysis by 0.010 M Cu(NO3)2 in water accelerates the reaction by a factor of 79 300.
		The kinetics of the catalyzed reaction were analyzed in terms of equilibrium constants for complexation of the Lewis acid with 1a-e and rate constants for the reaction of the resulting complexes with 2.
		The modest solvent and substituent effects observed for the catalyzed reaction indicate that the change in charge separation during the activation process is not larger than the corresponding change for the uncatalyzed reaction.
	stratingh.eldoc.ub.rug.nl /root/EngbertsJBFN/1996/JAmChemSocOtto (228 words)

	Diels-Alder Reaction Mechanism - Science Articles :: Physics Post
		The Diels-Alder reaction is considered to be one of the most interesting and useful reactions found in organic chemistry, and is often used for the synthesis of six-membered rings.
		Alder Reaction of Hyponitrous Acid, Nitrosoalkanes, Nitrosoarenes, and Nitrosocarbonyl Compounds.
		This experiment was based on the idea that since reactions of unsymmetrical dienes or dienophiles have been shown to have unsymmetrical transition states, there is no evidence to suggest that the same is not true for symmetrical dienes or dienophiles.
	www.physicspost.com /articles.php?articleId=74 (1341 words)

	Diels-Alder Mechanism
		Since this reaction forms two new carbon-carbon bonds in a single step, it is a very useful and powerful reaction (one which earned Otto Diels and Kurt Alder a Nobel prize in chemistry for discovering it).
		One quirk of the Diels-Alder reaction is that the diene is required to be in the s-cis conformation in order for the Diels-Alder reaction to work.
		Typically, the Diels-Alder reaction works best when either the diene is substituted with electron donating groups (like -OR, -NR etc) or when the dienophile is substituted with electron-withdrawing groups (like -NO, -CN, -COR, etc).
	www.chemhelper.com /dielsalder.html (520 words)

	The Diels-Alder Reaction Of Phenylsulfonyl- Acetylene And Furan And Pyrrole Derivatives. Normal Vs. Tandem "Pincer" Reactions
		The Diels-Alder Reaction Of Phenylsulfonyl- Acetylene And Furan And Pyrrole Derivatives.
		Abstract: The Diels-Alder reaction between some furan derivatives and phenylsulfonylacetylene has been studied along the normal and "pincer" pathways.
		In the same reaction conditions N-tosylpyrrole and phenylsulfonylacetylene afford only the normal adduct.
	www.ch.ic.ac.uk /ectoc/echet98/pub/063 (80 words)

	Diels-Alder Reaction
		The simplest Diels-Alder Reaction is the reaction of 1,3-butadiene and ethylene to yield cyclohexene (Figure 1).
		The Diels-Alder reaction is a thermal cycloaddition whose mechanism involves the sigma-overlap of the pi-orbitals of the two unsaturated systems.
		To compare Diels-Alder reactions, it is a good approximation to study only the reaction enthalpies (Hess' law (3) enables us to calculate them easily with the outputs of the calculations which are often heats of formation).
	www.ch.ic.ac.uk /motm/porphyrins/introDA.html (1141 words)

	Diels-Alder reaction, note
		In the initial stages of a reaction this approximation may be justified: the pi homo and lumo extend further in space than the sigma orbitals and will overlap first.
		Consequently, all asymmetric orbitals in the reactants contribute to the new asymmetric orbitals of the reaction complex, and it is neither possible nor useful to relate these new orbitals to one or two starting MO's.
		For instance, orbital no. 6 is shown on the right: an anti-symmetric combination in which we could detect at least four C-H sigma orbitals (the remaining two to a lesser extent).
	www.cmbi.kun.nl /~borkent/wetche/mb28/daorbs.html (299 words)

	HKUST Institutional Repository: Item 1783.1/535
		The above dienes and enones were submitted in the Diels-Alder reaction by reacting in acetonitrile and in the presence of the catalyst trimethylsilyl trifluoromethanesulfonate.
		The use of the Diels-Alder reaction is illustrated in the preparation of (4a'RS,8'SR,8a'RS)-2-(2'-methyl-3',4',4a',5',6',7',8',8a'-octahydronaphthalen-8'-yl)-acetic acid from 1SR,2SR,4aSR,8RS,8aRS)-8-(1'-hydroxyethan-2'-yl)-2-methyl-1,2,3,4,4a,5,8,8a-octahydro-1-naphthol.
		Each of (2R,3E,5E)- and (2S,3E,5E)-2-methyl-3,5-heptadien-1-ol were prepared from the respective enantiomers of 3-bromo-2-methylpropan-1-ol via conversion into the corresponding phosphonium salts, and reaction with (E)-2-butenal (crotonaldehyde); the alcohols were obtained as an inseparable 4:1mixture of E and Z isomers.
	hdl.handle.net /1783.1/535 (417 words)

	Diels-Alder
		When the reaction is being done, all the sulfolene does not have to break up before the Diels-Alder reaction can begin.
		Since there are six electrons moving in a circle, the transition state of the reaction is aromatic, like a benzene ring, and is therefore stabilized, meaning it is easier to get to.
		Likewise the electron-withdrawing carbonyl groups also make it easier for the reaction to happen, by lowering the energy of the lowest-unoccupied molecular orbital (LUMO) to approach (but still be higher than) the energy of the highest-occupied molecular orbital (HOMO) of the butadiene.
	lonestar.utsa.edu /mpenick/diels_alder.htm (327 words)

	Laboration 9: The Diels-Alder reaction
		One of the most often utilized reactions in organic chemistry is the Diels-Alder reaction in which a diene and a dienophile (an alkene) combine to form a cyclohexene.
		The Diels-Alder reaction is an example of a general type of reactions called pericyclic reactions.
		To investigate if the Diels-Alder reaction proceeds in one step it is useful to locate the possible transition state and take a look at the vibration which corresponds to the imaginary IR-frequency.
	www.oc.chalmers.se /spartanc/lab9.html (253 words)

	Synthesis of Flavonoids by Mentzer’s Reaction: Enhancement by Microwaves and Ionic Liquids
		The reaction with bis trimethylsilyl acetylene gave the 3,4-disilylfuran by the Diels-Alder retro Diels Alder reaction and loss of hydrogen cyanide.
		Substituted Pyridines and Furans were synthesized from 2,4,5-Trimethyloxazole (diene), and olefinic and acetylenic dienophiles by a microwave-assisted Diels-Alder reaction.
		Also because one of the aims of this experiment is to show a decrease in the reaction time using the microwave, all of the reactions had to be performed using the reflux in toluene, to serve as a comparison.
	www.mdpi.org /ecsoc/ecsoc-7/papers/E011/E011.htm (920 words)

	Chapter 10: Diels-Alder reaction
		The Diels-Alder reaction is stereospecific with respect to both the diene and the dienophile.
		The Diels-Alder reaction is a conjugate addition reaction of a conjugated diene to an alkene (the dienophile) to produce a cyclohexene.
		The two reactions shown above require harsh reaction conditions, but the normal Diels-Alder reaction is favoured by electron withdrawing groups on the electrophilic dienophile and by electron donating groups on the nucleophilic diene.
	www.chem.ucalgary.ca /courses/351/Carey5th/Ch10/ch10-5.html (297 words)

	Articles - Kurt Alder
		Alder received several honorary degrees and other awards, most famously the 1950 Nobel Prize in Chemistry which he shared with his teacher Diels for their work on what is now known as the Diels-Alder reaction.
		Kurt Alder (10 July 1902 â€“ 20 June 1958) was a German chemist who won the Nobel Prize in Chemistry jointly with Otto Paul Hermann Diels in 1950.
		Alder was born in the industrial area of KÃ¶nigshÃ¼tte in Upper Silesia, where he received his early schooling.
	www.centralairconditioners.net /articles/Kurt_Alder (281 words)

	Diels - Alder Tutorial
		The Diels - Alder reaction is a cycloaddtion reaction between a two conjugated double bonds (a diene) and a carbon carbon double bond or triple bond (dienophile).
		Below are interactive models of the favored endo and unfavored exo transition states for the Diels-Aldert reaction between cyclopentadiene and maleic anyhydride.
		The Diels - Alder reaction is named after Otto Diels and Kurt Alder.
	www.nku.edu /~russellk/tutorial/DA/DA.html (197 words)

	Diels-Alder Reaction
		This particular class of [4+2] cycloaddition reaction was discovered by Otto Paul Hermann Diels and his student Kurt Alder in Germany during the 1930s.
		Finally, since the reaction is concerted, the steriochemistry of both the diene and the dienophile are maintained.
		Pericyclic reactions on the other hand are characterized by a single concerted step that proceeds through a cyclic intermediate.
	www2.volstate.edu /CHEM/2020/Labs/Diels_Alder.htm (920 words)

	Diels-Alder reaction
		Diels, O.; Alder, K. Ann., 1928, 460, 98.
		Diels, O.; Alder, K.; Lubbert, W.; Naujokas, E.; Querberitz, F.; Rohl, K.; Segeberg, H. Ann., 1929, 470, 62.
		Diels, O.; Alder, K. Ber., 1929, 62, 2081, 2087.
	orgchem.chem.uconn.edu /namereact/dielsalder.html (66 words)

	Diels-Alder Reaction
		The Diels-Alder reaction was discovered in 1928 by German chemists Otto Diels and Kurt Alder, who received the Nobel Prize in chemistry in 1950 for their work towards understanding this 4+2 cycloaddition.
		The Diels-Alder reaction continues to be a widely used reaction in modern organic synthesis because in one step two carbon-carbon bonds are made in a stereoselective way.
		In the Diels-Alder reaction, an alkene or an alkyne react with a conjugated diene to form an unsaturated six-membered ring.
	www.chem.umn.edu /services/lecturedemo/info/Diels-Alder_Reaction.html (298 words)

	Kurt Alder -- Encyclopædia Britannica
		German chemist who was the corecipient, with Otto Diels, of the Nobel Prize for Chemistry in 1950 for their development of the Diels-Alder reaction, or diene synthesis, a widely used method of synthesizing cyclic organic compounds.
		The characteristic reaction of alkanes is substitution; that of alkenes and alkynes is addition to the double or triple bond.
		It is characterized by long, thin antennae and two pairs of large, net-veined wings, in spite of which, the adult alder fly is a weak flyer.
	www.britannica.com /eb/article-9005529 (684 words)

	Molecular Orbitals in Diels-Alder Reaction
		Diels-Alder reaction is a cycloaddition reaction between a conjugated diene and dienophile.
		Diels-Alder Reaction by Francis A. Carey at University of Calgary
		The reaction is highly stereoselectivive: cis-substituted dienophiles yield cis-substituted cyclohexenes and trans-substituted dienophiles yield trans-substituted cyclohexenes.
	www.chem.ucsb.edu /~kalju/chem109C/DielsAlder.html (228 words)

	Diels-Alder Reaction
		The reaction is concerted and the stereochemistry is conserved.
		A good reaction is obtained when usig electron-rich dienes and electron-low dienophiles.
		The reaction can be thermally induced or induced by light.
	fachschaft.cup.uni-muenchen.de /~schleifi/reaktion/reaction/dielsald.html (81 words)

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