Facial selectivity in the inverse-electron-demand Diels-Alder reaction: additions to 1,2,3,4,5-pentachloro-5-methoxy-1,3-cyclopentadiene

Burry, L. C.; Bridson, John N.; Burnell, D. Jean

doi:10.1021/jo00123a033

Cited by 22 publications

(7 citation statements)

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“…The degree of diene deformation must be determined to some extent by the steric demands of the dienophile, but with dienophiles of similar steric bulk but different reactivity one should nevertheless expect similar facial selectivity. This is consistent with studies in which dienes have been reacted with a number of dienophiles. ,, …”

Section: Resultssupporting

confidence: 91%

“…When the substituent at C5 is a sulfide there is little facial selectivity. , Other heteroatoms, such as silicon, selenium, bromine, , iodine, , and more oxygenated sulfur-containing functional groups 12 direct addition almost exclusively anti to the heteroatom. We demonstrated that facial selectivity with dienes of this type is the same in inverse-electron-demand reactions as it is in normal Diels−Alder reactions whereas additions to benzene oxide are clearly not controlled by a stereoelectronic effect .…”

Section: Introductionmentioning

confidence: 80%

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An ab Initio Study of Facial Selectivity in the Diels−Alder Reaction

Pye

et al. 1998

J. Org. Chem.

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Facial selectivities in the Diels-Alder reactions of 5-substituted 1,3-cyclopentadienes with a variety of dienophiles are predicted reliably at the ab initio HF/6-31G level. The ranges of activation energies for syn addition are large relative to those for anti addition, which are all similar to the activation energy for cyclopentadiene itself. Partitioning the activation energy into diene deformation, dienophile deformation, and diene-dienophile interaction energies shows that the major factor in determining facial selectivity is in the energy required to deform the diene into its transition state geometry. Deformation of the 5-fluoro-, 5-hydroxy-, and 5-amino-1,3-cyclopentadienes into their syn transition state geometries is predicted to require less energy than deformation of cyclopentadiene itself, which is in accord with experimental observation of syn addition with these dienes. The first definition of an ab initio steric factor is presented which correlates very well with syn activation energies. This indicates that facial selectivity with these dienes is primarily due to steric hindrance between the dienophile and the plane-nonsymmetric groups on the diene. However, we have also identified a significant lone pair-lone pair interaction with the reacting nitrogens when the dienophile is 1,2,4-triazoline-3,5-dione.

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Section: Resultssupporting

confidence: 91%

Section: Introductionmentioning

confidence: 80%

An ab Initio Study of Facial Selectivity in the Diels−Alder Reaction

Pye

et al. 1998

J. Org. Chem.

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“…Hence, while cyclopentadienylberyllium hydride (CpBeH), in which the interaction is highly ionic, is a highly symmetric C 5v structure, 51,52 the amino- 53 or the hydroxy-derivative presents low or no-symmetry. Among the three possible isomers which can be formed by substitution of one of the five ring-carbon atoms, namely 1-, 2-and 5-substituted 1,3-cyclopentadienes (see Scheme 1), the latter have received particular attention because: (i) structurally speaking most of these compounds can be considered highly Scheme 1 fluxional systems, 6,32,36,39,46,[54][55][56] which very often easily undergo degenerate 1,5-suprafacial shifts, usually known as circumambulatory rearrangements, (ii) in Diels-Alder reactions they show a facial selectivity by adding the dienophiles preferentially syn to the heteroatom when substituted at C5 with nitrogen, oxygen or fluorine, [57][58][59][60][61][62][63][64] (iii) for substituents of groups 13, 14, and 15 (CpX, X = BH 2 , AlH 2 , GaH 2 , CH 3 , SiH 3 , GeH 3 , PH 2 , AsH 2 ) they exhibit a rather enhanced acidity with respect to the unsubstituted parent compound, 53,56,65 associated to changes in the aromatization of the systems and to significant anionic hyperconjugation effects, which reinforced the C-X bond in the anionic species. The alkaline-earth derivatives (CpX, X = BeH, MgH, CaH) are an exception, 52 as they are predicted to be weaker acids than the unsubstituted parent compound.…”

Section: Introductionmentioning

confidence: 99%

Stability trends and tautomerization of chalcocyclopentadienes. The role of aromaticity

et al. 2011

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International audienceThe stability trends and tautomerization processes within the family of chalcocyclopentadienes (CpXH, X = O, S, Se, Te) have been investigated through the use of high-level G3B3 and G2 ab initio, as well as B3LYP density functional theory calculations. All methods predict the 5-substituted derivative to be the least stable tautomer, with the only exception of the Te derivative. For X = O, Se the dominant forms are the 2- and the 1-substituted derivatives, respectively, whereas for S, an equal distribution of the two forms is predicted. The enhanced stability of the 5-substituted compound on going from O to Te is due to a parallel increase of the aromaticity of the system, through a charge donation from the C-X bond toward the five membered ring. Independently of the nature of the chalcogen heteroatom, the global minimum of the PES is the asymmetric keto structure 2-cyclopenten-1-one. Its enhanced stability with respect to the symmetric keto form 3-cyclopenten-1-one is due to a more favorable conjugation between the C[double bond, length as m-dash]X and the C[double bond, length as m-dash]C π-systems. This interaction steadily increases on going from O to Te. The barriers connecting the keto and the enolic forms are rather high, as those connecting the enolic forms among each other. Hence, an important conclusion is that, in the gas-phase, if the 5-substituted derivative is formed, it should be observable no matter the nature of the chalcogen heteroatom

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“…In addition, the synthesis of porous organic polymers via Diels–Alder cycloaddition polymerization could lead to the formation of two isomeric adducts, which in turn can affect the porosity of the resulting polymers. Thus, one approach to control distribution isomers within the GNFs is to tune (Scheme ) electronic properties of dicyclopentanedienone by varying its substituents. , Notably, it has already been shown that electronic properties of conjugated dienes in the [4 + 2] cycloaddition plays a major role in controlling the regioselectivity of the Diels–Alder reaction. , Accordingly, in an effort to control textural and gas sorption properties of GNFs, here, we synthesized (Scheme ) GNFs incorporating GNRs with precisely positioned substituents, namely, −OMe (GNF-0), −H (GNF-1), −CF 3 (GNF-2), and −F (GNF-3). Importantly, decreasing the π-electron density of dicyclopentanedienone led to an increase in the formation of trans isomer as evidenced from the detailed analysis of model compounds, which, in turn, gave rise to higher surface area GNFs (up to 755 m 2 g –1 ).…”

Section: Introductionmentioning

confidence: 99%

“…20,21 Notably, it has already been shown that electronic properties of conjugated dienes in the [4 + 2] cycloaddition plays a major role in controlling the regioselectivity of the Diels−Alder reaction. 22,23 Accordingly, in an effort to control textural and gas sorption properties of GNFs, here, we synthesized (Scheme 1) GNFs incorporating GNRs with precisely positioned substituents, namely, −OMe (GNF-0), −H (GNF-1), −CF 3 (GNF-2), and −F (GNF-3). Importantly, decreasing the π-electron density of dicyclopentanedienone led to an increase in the formation of trans isomer as evidenced from the detailed analysis of model compounds, which, in turn, gave rise to higher surface area GNFs (up to 755 m 2 g −1 ).…”

Section: Introductionmentioning

confidence: 99%

Edge-Functionalized Graphene Nanoribbon Frameworks for the Capture and Separation of Greenhouse Gases

et al. 2017

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We demonstrate a bottom-up synthetic approach for the synthesis of graphene nanoribbon frameworks (GNFs) incorporating edge-functionalized graphene nanoribbons via the Diels−Alder cycloaddition polymerization and a subsequent FeCl 3 -catalyzed cyclodehydrogenation reactions. This approach not only allowed us to precisely position substituents, namely, −OMe (GNF-0), −H (GNF-1), −CF 3 (GNF-2), and −F (GNF-3), but also enabled to tune textural properties and gas affinity of resulting frameworks. GNFs exhibited promising physical properties such as high surface areas (up to 755 m 2 g −1 ) and excellent physicochemical and thermal stabilities (up to 400 °C). Narrow pore size distribution and the presence of large aromatic units led to high affinity toward gases such as CO 2 (27.4−30.9 kJ mol −1 at 1 bar), CH 4 (21.3−26.0 kJ mol −1 at 1 bar), and H 2 (6.5−8.2 kJ mol −1 at 1 bar). Notably, GNFs also showed promising CO 2 /CH 4 breakthrough separation performance for natural gas sweetening and landfill gas separations at 298 K. The edge-functionalization of GNFs with −CF 3 and −F significantly improved their affinity toward perfluorocarbons and CFCs, which are classified as potent greenhouse gases. Compared to GNF-3, GNF-2 containing −CF 3 moieties showed much higher uptake capacity toward CFC-113 (67 wt % at 298 K).

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Facial selectivity in the inverse-electron-demand Diels-Alder reaction: additions to 1,2,3,4,5-pentachloro-5-methoxy-1,3-cyclopentadiene

Cited by 22 publications

References 0 publications

An ab Initio Study of Facial Selectivity in the Diels−Alder Reaction

An ab Initio Study of Facial Selectivity in the Diels−Alder Reaction

Stability trends and tautomerization of chalcocyclopentadienes. The role of aromaticity

Edge-Functionalized Graphene Nanoribbon Frameworks for the Capture and Separation of Greenhouse Gases

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