Novel double [6 + 4] cycloaddition of tropone to dimethylfulvene

Houk, K. N.; Luskus, L. J.; Bhacca, N. S.

doi:10.1021/ja00724a077

Cited by 106 publications

(48 citation statements)

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“…Although nitrile oxide cycloadditions to dienes (e.g., norbornadienes, vide supra) and polyenes (e.g., fulvene) 21 have been reported in the literature, to our knowledge, selectivities in the cycloaddition of nitrile oxides to systems possessing multiple p-faces has not been investigated. 22,23 Herein, we report the remarkable selectivities observed in the cycloaddition of nitrile oxides to representative tricyclic systems.…”

Section: Introductionmentioning

confidence: 99%

Selectivities in the 1,3-dipolar cycloaddition of nitrile oxides to dicyclopentadiene and its derivatives

et al. 2004

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Section: Introductionmentioning

confidence: 99%

Selectivities in the 1,3-dipolar cycloaddition of nitrile oxides to dicyclopentadiene and its derivatives

et al. 2004

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“…Shortly thereafter, Cookson et al [3] and Ito and coworkers [4] reported that cyclopentadiene and tropone react at 80°C to give the exo [6 + 4] adduct stereospeci®cally. Houk and Woodward [5,6] reported several [6 + 4] cycloadditions of cyclopentadienones with tropone and cycloheptatriene, in competition with [4 + 2] and [8 + 2] processes (see Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

Transition structures and exo/endo stereoselectivities of concerted [6 + 4] cycloadditions with density functional theory

Goldstein

Beno

Houk

1999

Theoretical Chemistry Accounts: Theory, Computation, and Modeli

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Density functional theory transition structures were located for three concerted [6 + 4] cycloaddition reactions involving cis-hexatriene and butadiene, cyclopentadiene and cycloheptatriene, and cyclopentadiene and tropone. Geometries, energies, and entropies were computed at the Becke3LYP/6-31G* level. The activation energy of the concerted [6 + 4] cycloaddition of hexatriene and butadiene is 33.3 kcal/mol, about 8 kcal/mol above the activation energy of the butadiene plus ethylene [4 + 2] cycloaddition. The endo concerted [6 + 4] transition state is 1.1 kcal/mol higher than the exo. The [6 + 4] reaction of cyclopentadiene and cycloheptatriene has a barrier of 25.9 kcal/mol, while the cyclopentadiene± tropone barrier drops to 20.7 kcal/mol.

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“…In 1970, Houk et al introduced the concept of “ periselectivity ” as the selective formation of one of the thermally allowed pericyclic reaction products [ 56 , 57 ]. However, as the pericyclic mechanism has been recently ruled out [ 11 ], the term “periselectivity” has no sense.…”

Section: Resultsmentioning

confidence: 99%

A Molecular Electron Density Theory Study of the Competitiveness of Polar Diels–Alder and Polar Alder-ene Reactions

2018

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The competitiveness of the BF3 Lewis acid (LA) catalyzed polar Diels–Alder (P-DA) and polar Alder-ene (P-AE) reactions of 2-methyl-1,3-butadiene, a diene possessing an allylic hydrogen, with formaldehyde has been studied within the Molecular Electron Density Theory (MEDT) at the MPWB1K/6-311G(d,p) computational level. Coordination of BF3 LA to the oxygen of formaldehyde drastically accelerates both reactions given the high electrophilic character of the BF3:formaldehyde complex. As a consequence, these reactions present a very low activation enthalpy—less than 2.2 kcal·mol−1—thus becoming competitive. In dioxane, the P-AE reaction is slightly favored because of the larger polar character of the corresponding transition state structure (TS). In addition, the Prins reaction between hexahydrophenanthrene and the BF3:formaldehyde complex has also been studied as a computational model of an experimental P-AE reaction. For this LA-catalyzed reaction, the P-DA reaction presents very high activation energy because of the aromatic character of the dienic framework. The present MEDT study allows establishing the similarity of the TSs associated with the formation of the C–C single bond in both reactions, as well as the competitiveness between P-AE and P-DA reactions when the diene substrate possesses at least one allylic hydrogen, thus making it necessary to be considered by experimentalists in highly polar processes. In this work, the term “pseudocyclic selectivity” is suggested to connote the selective formation of structural isomers through stereoisomeric pseudocyclic TSs.

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Novel double [6 + 4] cycloaddition of tropone to dimethylfulvene

Cited by 106 publications

References 2 publications

Selectivities in the 1,3-dipolar cycloaddition of nitrile oxides to dicyclopentadiene and its derivatives

Selectivities in the 1,3-dipolar cycloaddition of nitrile oxides to dicyclopentadiene and its derivatives

Transition structures and exo/endo stereoselectivities of concerted [6 + 4] cycloadditions with density functional theory

A Molecular Electron Density Theory Study of the Competitiveness of Polar Diels–Alder and Polar Alder-ene Reactions

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