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Retro-Diels Alder

C, b.p. 170 C (decomp.), has a characteristic odour. It is the Diels-Alder product of cyclopentadiene reacting with itself, the exo-form being formed most rapidly but the endo-form is thermodynamically favoured. At temperatures above ISO C a retro-Diels-Alder reaction occurs and cyclopentadiene monomer is regenerated see diene reactions. [Pg.135]

In summary, it seems that for most Diels-Alder reactions secondary orbital interactions afford a satisfactory rationalisation of the endo-exo selectivity. However, since the endo-exo ratio is determined by small differences in transition state energies, the influence of other interactions, most often steric in origin and different for each particular reaction, is likely to be felt. The compact character of the Diels-Alder activated complex (the activation volume of the retro Diels-Alder reaction is negative) will attenuate these eflfects. The ideas of Sustmann" and Mattay ° provide an attractive alternative explanation, but, at the moment, lack the proper experimental foundation. [Pg.7]

Analogously, the effect of micelles on the rate of the unimolecular retro Diels-Alder reaction has been studied. Also here only a modest retardation" or acceleration" is observed. Likewise, the presence of micelles has been reported to have a modest influence on an intramolecular Diels-Alder reaction . Studies on the endo-exo selectivity of a number of different Diels-Alder reactions in micellar media lead to comparable conclusions. Endo-exo selectivities tend to be somewhat smaller in micellar solutions than in pure water, but still are appreciably larger than those in organic media In contrast, in microemulsions the endo-exo selectivity is reduced significantly" ... [Pg.132]

The observation that in the activated complex the reaction centre has lost its hydrophobic character, can have important consequences. The retro Diels-Alder reaction, for instance, will also benefit from the breakdown of the hydrophobic hydration shell during the activation process. The initial state of this reaction has a nonpolar character. Due to the principle of microscopic reversibility, the activated complex of the retro Diels-Alder reaction is identical to that of the bimoleciilar Diels-Alder reaction which means this complex has a negligible nonpolar character near the reaction centre. O nsequently, also in the activation process of the retro Diels-Alder reaction a significant breakdown of hydrophobic hydration takes placed Note that for this process the volume of activation is small, which implies that the number of water molecules involved in hydration of the reacting system does not change significantly in the activation process. [Pg.168]

We conclude that the beneficial effects of water are not necessarily limited to reactions that are characterised by a negative volume of activation. We infer that, apart from the retro Diels-Alder reaction also other reactions, in which no significant reduction or perhaps even an increase of solvent accessible surface area takes place, can be accelerated by water. A reduction of the nonpolar nature during the activation process is a prerequisite in these cases. [Pg.168]

In the case of the retro Diels-Alder reaction, the nature of the activated complex plays a key role. In the activation process of this transformation, the reaction centre undergoes changes, mainly in the electron distributions, that cause a lowering of the chemical potential of the surrounding water molecules. Most likely, the latter is a consequence of an increased interaction between the reaction centre and the water molecules. Since the enforced hydrophobic effect is entropic in origin, this implies that the orientational constraints of the water molecules in the hydrophobic hydration shell are relieved in the activation process. Hence, it almost seems as if in the activated complex, the hydrocarbon part of the reaction centre is involved in hydrogen bonding interactions. Note that the... [Pg.168]

The type of enforced hydrophobic effect that is operative in the retro Diels-Alder reaction cannot be referred to an enforced hydrophobic interaction, since there is no coming together, but rather a separation of nonpolar molecules during the reaction. It is better to refer to this process as an enforced hydrophobic effect. [Pg.170]

Under different conditions [PdfOAcj2, K2CO3, flu4NBr, NMP], the 1 3 coupling product 86 with 4-aryl-9,10-dihydrophenanthrene units was obtained. The product 86 was transformed into a variety of polycyclic aromatic compounds such as 87 and 88[83], The polycyclic heteroarene-annulated cyclopen-tadicnc 90 is prepared by the coupling of 3-iodopyridine and dicyclopentadiene (89), followed by retro-Diels Alder reaction on thermolysis[84]. [Pg.141]

The reaction of o-iodophenol, norbornadiene and CO proceeds via alkene and CO insertions to afford the lactone 562, which is converted into coumarin (563) by the retro-Diels-Alder reaction. In this coumarin synthesis, norbona-diene behaves as a masked acetylene[4)3],... [Pg.205]

In a novel approach to vitamin K, Hoffmann-La Roche has exploited the potential acidity at C-3 as a means to attach the side chain of vitamin (36). Menadione was reacted with cyclopentadiene to yield the Diels-Alder adduct. The adduct is treated with base and alkylated at C-3 with phytyl chloride. A retro Diels-Alder reaction yields vitamin K. Process improvements in this basic methodology have been claimed by Japanese workers (37). [Pg.153]

The mass spectrum of 2-pyrone shows an abundant molecular ion and a very prominent ion due to loss of CO and formation of the furan radical cation. Loss of CO from 4-pyrone, on the other hand, is almost negligible, and the retro-Diels-Alder fragmentation pathway dominates. In alkyl-substituted 2-pyrones loss of CO is followed by loss of a hydrogen atom from the alkyl substituent and ring expansion of the resultant cation to the very stable pyrylium cation. Similar trends are observed with the benzo analogues of the pyrones, although in some cases both modes of fragmentation are observed. Thus, coumarins. [Pg.22]

In 1973 two papers appeared almost simultaneously (73T101, 73CPB2026) describing the formation, as a minor product, of 3,4,5-trimethoxycarbonyl-l-phenylpyrazole (346) in the reaction between benzaldehyde phenylhydrazone and DMAD (EC=CE). To account for the formation of (346) George et al. (73T101) proposed a tentative mechanism (Scheme 29) involving a Diels-Alder reaction of type (a Figure 25), followed by a retro-Diels-Alder elimination of methyl phenylpropiolate (347). [Pg.248]

HC(17)1, p. 53), and by retro-Diels-Alder reaction of the adduct from norbornadiene and fulminic acid <67AG(E)456). [Pg.83]

The primary and secondary products of photolysis of common diazirines are collected in Table 4. According to the table secondary reactions include not only isomerization of alkenes and hydrogen elimination to alkynes, but also a retro-Diels-Alder reaction of vibrationally excited cyclohexene, as well as obvious radical reactions in the case of excited propene. [Pg.226]

Also the mirror image of the strueture I, eorreetly denoted as exo-3,10-dihydroxy-3,5,8,10-tetra-methyltrieyelo[6.2.2.0 ]dodeea-5,l 1-diene-4,9-dione, would be possible sinee enantiomers are not differentiated by NMR. A retro-Diels-Alder fragmentation of I to CsH/oO explains why the moleeular ion eorresponding to the moleeular formula C16//20O4 is not deteeted in the mass spee-trum. The metabolite I eould be formed by Diels-Alder dimerisation of 1,5-dimethyleyelohexa-l,3-dien-5-ol-6-one J as the primary metabolite which acts as diene and dienophile as well... [Pg.222]

Molecular orbital calculations indicate that cyclo C-18 carbyne should be relatively stable and experimental evidence for cyclocarbynes has been found [25], Fig. 3B. Diederich et al [25] synthesised a precursor of cyclo C-18 and showed by laser flash heating and time-of flight mass spectrometry that a series of retro Diels-Alder reactions occurred leading to cyclo C-18 as the predominant fragmentation pattern. Diederich has also presented a fascinating review of possible cyclic all-carbon molecules and other carbon-rich nanometre-sized carbon networks that may be susceptible to synthesis using organic chemical techniques [26]. [Pg.8]

Scheme 9.3. Correlation between for Retro-Diels-Alder Reaction and Resonance Stabilization of Aromatic Products... Scheme 9.3. Correlation between for Retro-Diels-Alder Reaction and Resonance Stabilization of Aromatic Products...
These amines gave, with methyl propiolate, products of Michael mono- and bis-addition. Adducts underwent further reaction leading to triazolo[4,5-/]quinolones 181, after retro Diels-Alder reaction and acetylene elimination to its methoxycar-... [Pg.258]

The concept of transient chirality in stereoselective synthesis of five-membered heterocycles using the retro-Diels-Alder methodology 99CRV1163. Five-member heteryladamantanes 99ZOR183. [Pg.245]

Retro Diels-Alder reaction of nitrogen bridgehead compound 415 at 100 °C afforded 6,7,8,9-tetrahydro-4//-pyrido[l,2-u]pyrimidin-4-one and cyclobutadiene (97SC195). [Pg.254]

Although furan is usually a poor diene in the Diels-Alder reaction, the chiral copper reagent 24b promotes its asymmetric addition to acryloyloxazolidinone to afford the 7-oxabicyclo[2.2.1]hept-2-ene derivative in high optical purity (Scheme 1.40). Because a retro-Diels-Alder reaction occurs above -20 °C, the reaction must be performed at low temperature (-78 °C) to obtain a high optical yield. The bicy-... [Pg.29]

R,R-DBFOX/Ph 250 reaction course 303 regioselectivity 216 retro-Diels-Alder reaction 29 reversal of enantioselectivity 224 rhodium... [Pg.331]


See other pages where Retro-Diels Alder is mentioned: [Pg.11]    [Pg.22]    [Pg.23]    [Pg.61]    [Pg.132]    [Pg.209]    [Pg.210]    [Pg.401]    [Pg.22]    [Pg.23]    [Pg.66]    [Pg.174]    [Pg.65]    [Pg.37]    [Pg.193]    [Pg.679]    [Pg.679]    [Pg.829]    [Pg.830]    [Pg.466]    [Pg.924]    [Pg.73]    [Pg.51]    [Pg.61]    [Pg.62]   
See also in sourсe #XX -- [ Pg.67 ]

See also in sourсe #XX -- [ Pg.248 ]

See also in sourсe #XX -- [ Pg.248 ]

See also in sourсe #XX -- [ Pg.18 , Pg.58 ]

See also in sourсe #XX -- [ Pg.23 ]

See also in sourсe #XX -- [ Pg.107 ]

See also in sourсe #XX -- [ Pg.213 ]

See also in sourсe #XX -- [ Pg.23 ]

See also in sourсe #XX -- [ Pg.115 , Pg.135 , Pg.139 , Pg.142 ]

See also in sourсe #XX -- [ Pg.248 ]

See also in sourсe #XX -- [ Pg.173 ]

See also in sourсe #XX -- [ Pg.642 , Pg.672 , Pg.673 ]




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1.2- Diazines via retro Diels-Alder reactions

1.3- Butadiene-2,3-dicarbonitrile via retro Diels-Alder reaction

1.3- Butadiene-2,3-dicarboxylic acid via retro Diels-Alder reaction

2-Alkenoic acids, 2-alkylmethyl esters synthesis via retro Diels-Alder reaction

2-Aza-l,3-dienes via retro Diels-Alder reactions

2-Silapropene, 2-methylsynthesis via retro Diels-Alder reaction

2.5- Heptadiene via retro Diels-Alder reaction

7-Silabicyclo octadiene retro Diels-Alder reaction

A-Cartopterone via retro Diels-Alder reaction

A-Caryopterone via retro Diels-Alder reaction

Acetylenedicarbonyl chloride via retro Diels-Alder reaction

Acrylates via retro Diels-Alder reaction

Aldehydes synthesis via retro Diels-Alder reactions

Alkenes retro-Diels-Alder reaction

Alkenes synthesis via retro Diels-Alder reactions

Allenes, vinylanthracene adduct retro Diels-Alder reaction

And retro Diels-Alder reactions

Anthracene retro-Diels-Alder reaction

Anthracenedione retro-Diels—Alder

Anthranol retro Diels-Alder reaction

Aspidosperma alkaloids, deethylsynthesis via retro Diels-Alder reactions

Azetines via retro Diels-Alder reactions

Azomethane via retro Diels-Alder reactions

Benzenes synthesis via retro Diels-Alder reaction

Bicyclo hept-2-enes via retro Diels-Alder reactions

Butatriene via retro Diels-Alder reaction

Clavulones via retro Diels-Alder reactions

Conduritol via retro Diels-Alder reactions

Crotepoxide via retro Diels-Alder reactions

Crotonaldehyde via retro Diels-Alder reaction

Cumulenes via retro Diels-Alder reaction

Cycloaddition reactions retro-Diels-Alder reaction

Cycloalkenes retro-Diels-Alder reaction

Cyclobutene, 3,3-dimethoxysynthesis via retro Diels-Alder reaction

Cyclobutene, dimethylenesynthesis via retro Diels-Alder reactions

Cyclohexenes retro-Diels-Alder reaction

Cyclopentadiene retro Diels-Alder reaction

Cyclopentadienone epoxides via retro Diels-Alder reactions

Cyclopentanoids via retro Diels-Alder reactions

Cyclopentenols via retro Diels-Alder reactions

Cyclopentenones synthesis via retro Diels-Alder reactions

Cyclopropene, 3,3-difluorosynthesis via retro Diels-Alder reactions

Diels retro Dids-Alder reaction

Diels-Alder reaction, Retro-hetero

Diels—Alder route, retro

Enediols via retro Diels-Alder reactions

Enol lactones via retro Diels-Alder reactions

Enols via retro Diels-Alder reactions

Epiepoformine via retro Diels-Alder reactions

Epiepoxydon via retro Diels-Alder reactions

Epipentenomycin via retro Diels-Alder reactions

Epoformine via retro Diels-Alder reactions

Epoxydon via retro Diels-Alder reactions

Esters synthesis via retro Diels-Alder reactions

Ethylenamine via retro Diels-Alder reactions

Fulvene, 6,6-dimethylcycloaddition reactions retro Diels-Alder reaction

Fulvenes retro Diels-Alder reaction

Furan, 2,3-dihydro-2,3-dimethylenesynthesis via retro Diels-Alder reactions

Furan, 2,5-dihydro-3,4-dimethylsynthesis via retro Diels-Alder reactions

Furan, tetramethylenetetrahydrosynthesis via retro Diels-Alder reactions

Furo pyridine via retro Diels-Alder reactions

Heterocyclic compounds synthesis via retro Diels-Alder reactions

Heterotropanone via retro Diels-Alder reaction

Hinokinin via retro Diels-Alder reactions

Hydrocarbons synthesis via retro Diels-Alder reaction

Imidazole, 2- synthesis via retro Diels-Alder reaction

Imidazoles, 2-vinylsynthesis via retro Diels-Alder reactions

Indene, 2-vinylsynthesis via retro Diels-Alder reactions

Ipsenol via retro Diels-Alder reaction

Isognididione via retro Diels-Alder reactions

Isoheterotropanone via retro Diels-Alder reaction

Isoindoles synthesis via retro Diels-Alder reactions

Isoindoles via retro Diels-Alder reactions

Isopropenyl acetoacetate via retro Diels-Alder reactions

Isoxazoles, 3-arylsynthesis via retro Diels-Alder reactions

Jasmone via retro Diels-Alder reactions

Juncusol via retro Diels-Alder reaction

Ketones synthesis via retro Diels-Alder reactions

Kinetics retro-Diels-Alder reaction

Ligularone via retro Diels-Alder reactions

Linalool via retro Diels-Alder reaction

Malonic acid, methylenediesters synthesis via retro Diels-Alder reaction

Mass spectral fragmentation retro Diels-Alder

Matsutake alcohol via retro Diels-Alder reaction

Methanimine via retro Diels-Alder reactions

Multifidene via retro Diels-Alder reactions

Nerolidol via retro Diels-Alder reaction

Nitrogen diene synthesis via retro Diels-Alder reaction

Norbomen retro-Diels-Alder reaction

Norbomenes retro-Diels-Alder reaction

O-Xylylenes via retro Diels-Alder reaction

Occidentalol via retro Diels-Alder reaction

Oxirene retro Diels-Alder reactions

Pentatetraene via retro Diels-Alder reaction

Pentenomycin via retro Diels-Alder reactions

Pericyclic retro-Diels-Alder reaction

Petasalbine via retro Diels-Alder reactions

Phenanthrenes, dihydrosynthesis via retro Diels-Alder reaction

Phosphines, vinylsynthesis via retro Diels-Alder reactions

Phthalic acid synthesis via retro Diels-Alder reaction

Phyllostine via retro Diels-Alder reactions

Plumbagin via retro Diels-Alder reaction

Propadienethione via retro Diels-Alder reactions

Propellanes via retro Diels-Alder reactions

Properties of the Retro-Diels-Alder Reaction

Punaglandins via retro Diels-Alder reactions

Pyrenochaetic acid via retro Diels-Alder reaction

Pyridines via retro Diels-Alder reactions

Pyrimidinone via retro Diels-Alder reactions

Pyrroles via retro Diels-Alder reactions

Quinanes via retro Diels-Alder reactions

Quinone epoxides via retro Diels-Alder reactions

Retro Diels-Alder cleavage

Retro Diels-Alder reaction

Retro Diels-Alder reaction additional application

Retro Diels-Alder reaction synthesis of actinidine

Retro Diels-Alder reaction synthesis of crotepoxide

Retro Diels-Alder reaction synthesis of epiepoxydon

Retro Diels-Alder reaction synthesis of epoformine

Retro Diels-Alder reaction synthesis of epoxydon

Retro Diels-Alder reaction synthesis of ligularone

Retro Diels-Alder reaction synthesis of petasalbine

Retro Diels-Alder reaction synthesis of phyllostine

Retro Diels-Alder rearrangement

Retro Diels—Alder cycloreversion

Retro Diels—Alder reaction reactions Lewis

Retro aza Diels-Alder reactions in aqueous media

Retro aza-Diels-Alder reactions

Retro “inverse electron-demand Diels-Alder reactions

Retro-Diels-Alder fission

Retro-Diels-Alder fragmentation

Retro-Diels-Alder process

Retro-Diels-Alder reaction alkene protection

Retro-Diels-Alder reaction carbon monoxide from

Retro-Diels-Alder reaction enamine synthesis

Retro-Diels-Alder reaction ketones

Retro-Diels-Alder reaction requirements

Retro-Diels-Alder reactions of ionized cyclohexenes

Retro-Diels-Alder reactions, femtosecond time

Retro-Diels-Alder type cleavage

Retro-Diels-Alder type cleavage CO2 elimination

Retro-Diels-Alder type transform

Retro-Diels—Alder reactions photochemical

Retro-cycloadditions Diels-Alder reactions

Sarkomycin via retro Diels-Alder reaction

Senepoxyde via retro Diels-Alder reactions

Silenes via retro Diels-Alder reaction

Stereochemistry and the Retro Diels-Alder Reaction

Terrein via retro Diels-Alder reactions

The retro Diels-Alder reaction

Thieno furan via retro Diels-Alder reactions

Thio compounds synthesis via retro Diels-Alder reaction

Thioacrolein via retro Diels-Alder reaction

Thioacrylamides via retro Diels-Alder reaction

Thioaldehydes synthesis via retro Diels-Alder reactions

Thioformaldehyde via retro Diels-Alder reactions

Tricyclo tetradeca-l ,4,13-triene via retro Diels-Alder reactions

Tricyclodecenols, exo-methylenesynthesis via retro Diels-Alder reactions

Trienes synthesis via retro Diels-Alder reactions

Tropidine retro Diels-Alder reaction

Tropones synthesis via retro Diels-Alder reactions

Verrucarine via retro Diels-Alder reactions

Vinyl acetoacetate via retro Diels-Alder reactions

Vinyl alcohols via retro Diels-Alder reactions

Vinyl ethers via retro Diels-Alder reactions

Vinylcyclohexenes, radical cations retro-Diels-Alder reaction

Vinylidenamine via retro Diels-Alder reactions

Vitamin D2,22,23-epoxysynthesis via retro Diels-Alder reaction

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