Through-bond interactions of .beta.-carbonyl and .beta.-imine lone pairs with a cationic 2p orbital. Quantum calculations on bicyclo[2.2.2]oct-1-yl cation and derivatives

Carrupt, Pierre Alain; Vogel, Pierre

doi:10.1021/jo00309a012

Cited by 20 publications

(4 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Two aspects should be pointed out regarding the proposed reaction path: first, oxatrinorbornenone-derived ketals such as 11 have been found to be transformed into furan derivatives by treatment with fluorosulfonic acid (transformation of 11 into 12) [12] or Hg(NO 3 ) 2 in MeCN (transformation of 11 into 13) [13] [14] (Scheme 3) 4 ). Second, the alignment of the n(N) orbital with the s(C(1)ÀC(2)) bond (case of the (Z)-isomer of 5) is probably the reason for the ease of the fragmentation as predicted by Carrupt and Vogel [6]. The MM2 [5] and PM3 calculations performed on (Z)-5 indicate an almost perfect alignment of the s(C(1)ÀC(2)) and n(N) orbitals.…”

mentioning

confidence: 94%

See 1 more Smart Citation

On the Reactivity of (7-Oxabicyclo[2.2.1]hept-5-en-2-ylidene)amines. Different Reaction Paths Leading to the Same Final Products

Arjona¹,

Csákÿ²,

Murcia³

et al. 2001

HCA

View full text Add to dashboard Cite

Dedicated to Prof. Andre¬ M. Braun on the occasion of his 60th birthdayThe reaction of amines, N-substituted by a 7-oxabicyclo[2.2.1]hept-5-en-2-ylidene moiety, either with PhSCl or mCPBA (meta-chloroperbenzoic acid) unexpectedly afforded the same type of furan derivatives by two different reaction paths. The results confirm the intervention of a homoconjugative, electron-releasing effect of the oxabicycloalkenylideneamine moieties, as predicted theoretically.

show abstract

mentioning

confidence: 94%

“…Quantum calculations by Carrupt and Vogel [6] have predicted that homoconjugated imino substituents can be electron-releasing-like carbonyl moieties.…”

mentioning

confidence: 99%

On the Reactivity of (7-Oxabicyclo[2.2.1]hept-5-en-2-ylidene)amines. Different Reaction Paths Leading to the Same Final Products

Arjona¹,

Csákÿ²,

Murcia³

et al. 2001

HCA

View full text Add to dashboard Cite

show abstract

“…Howhave been prepared or observed (e.g., 5 (12, 2 l), 6 (141,7 ever, numerous studies, both experimental (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) and (1 8), and 8 (1 9)). theoretical (23)(24)(25)(26)(27)(28), have shown that this destabilizing efIn some instances, such as a-cyano and a-keto carbocations, this unexpected level of stability can be attributed to '~u t h o r to whom correspondence may be addressed.…”

Section: Introductionmentioning

confidence: 99%

Computational determination of the relative stabilities of some nitro carbocations

Redfern¹,

Murray²,

Politzer³

1992

Can. J. Chem.

View full text Add to dashboard Cite

The relative stabilities of a group of nitro carbocations (derivatives of the methyl, cyclopropyl. and cyclopropenyl cations) are determined by means of trb irziiio SCF/3-2 I G calculations, and compared to the corresponding results for other substituent groups, both electron donating and withdrawing. The a-nitro carbocations are generally destabilized relative to the parent cation, but often to a lesser extent than anticipated from the strongly electron-withdrawing nature of NOZ. ' The optimized structures indicate that this is due to the stabilizing fomiation of an intramolecular ring involving the nitro group; however, this requires the proximity of a sufficiently positive carbon.Key Utilisant des mkthodes ab iniiio SCF/3-2 1 G , on a calculC les stabilitks relatives d'un certain nonibre de carbocations de derives nitres (derives des cations mkthyle, cyclopropyle et cyclopropCnyle) et on les a comparCes aux resultats correspondants obtenus avec d'autres substituants, tant Clectro-attracteurs que electro-donneurs. Les carbocations en a d'un nitro sont gCnCralement dCstabilisCs par rapport au cation parent; toutefois, ils le sont souvent nioins que ce qui avait tte anticipe sur la base de la nature tres electro-attractive du NO2. Les structures optimisees indiquent que ce resultat est dfi a la formation stabilisante d'un cycle intranioleculaire impliquant le groupe nitro; toutefois, ce cycle nkcessite la proximite d'un carbone suffisamment positif.

show abstract

“…Remarkably, the two conformers (1Bu" and 1Bd") have an unexpected side-chain conformation, with the CH,-CH, bond in a plane almost perpendicular to the plane of the aromatic rings. This suggests that, in addition to throughspace electrostatic stabilization described above, a through-bond stabilization [41] [42] of the radical cation by hyperconjugation (known as the frangomeric effect) could also be involved [43]. This effect requires a good alignment of the n and/or n electrons in the amide group, the CH,-CH, c bond, and the n orbital of the indole ring.…”

mentioning

confidence: 99%

Theoretical Parameters to Characterize Antioxidants. Part 2. The cases of melatonin and carvedilol

Migliavacca

Ancerewicz

Carrupt

et al. 1998

Helvetica Chimica Acta

View full text Add to dashboard Cite

This theoretical study focuses on two indole derivatives, melatonin (1) and carvedilol (8). with the objective of improving our understanding of the molecular mechanisms underlying their radical-scavenging activity. Quantum-mechanical calculations were carried out using the AM1 semi-empirical method, some results being conlirmed by nh initio (3-21'3) calculations. The quantum-chemical descriptor AH,, (relative adiabatic oxidation potential) and the shape of the SOMO (singly occupied molecular orbital) indicate that the stabilization of its radical cation can partially explain the well-documented antioxidant efficacy of melatonin. This stabilization may result froin electrostatic interactions and from a hyperconjugative effect existing in a family of conformers of the melatonin radical cation having the side chain almost perpendicular to the plane of the aromatic rings. Furthermore, 6-hydroxymelatonin (7) appears to be a better free-radical scavenger than melatonin (1) in agreement with experimentel results. According to the theoretical parameters AH", and AHab, (relative bond dissociation enthalpy). carvedilol (8) is not a good antioxidant, in contrast to its ring-hydroxylated metabolites whose powerful antioxidant effects are explained by the formation of an oxyl radical stabilized by delocalization over the carbazole nucleus.

show abstract

Through-bond interactions of .beta.-carbonyl and .beta.-imine lone pairs with a cationic 2p orbital. Quantum calculations on bicyclo[2.2.2]oct-1-yl cation and derivatives

Cited by 20 publications

References 4 publications

On the Reactivity of (7-Oxabicyclo[2.2.1]hept-5-en-2-ylidene)amines. Different Reaction Paths Leading to the Same Final Products

On the Reactivity of (7-Oxabicyclo[2.2.1]hept-5-en-2-ylidene)amines. Different Reaction Paths Leading to the Same Final Products

Computational determination of the relative stabilities of some nitro carbocations

Theoretical Parameters to Characterize Antioxidants. Part 2. The cases of melatonin and carvedilol

Contact Info

Product

Resources

About