A computational investigation on the sequential rearrangement mechanism of 2‐allyl‐2,4,5‐hexatrienaldehyde involving [1,5]‐hydrogen migration and 8π‐electrocyclization

Zhu, Yiming; Guo, Yong; Zhang, Youmin; Xie, Daiqian

doi:10.1002/jcc.20714

Cited by 5 publications

(2 citation statements)

References 41 publications

(60 reference statements)

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“…For example, Okamura synthesized an analogue of 9α,19-methano-1α,25-dihydroxyvitamin D 3 containing a cyclooctatriene system by mild hydrogenation of a trienyne followed by an 8π-electrocyclization . Flynn and Ma reported the synthesis of various stable cyclooctatrienes by subsequent [1,5]- or [1,7]-hydrogen migration followed by 8π electrocyclization . Only few other examples of isolated cyclooctatrienes were described …”

Section: Introductionmentioning

confidence: 99%

Understanding the Torquoselectivity in 8π-Electrocyclic Cascade Reactions: Synthesis of Fenestradienes versus Cyclooctatrienes

et al. 2009

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Unusual and novel polycyclic cyclooctatrienes, fenestradienes, and fenestrenes form readily from trienynes depending on the structure of the starting trienynes and the reaction conditions. The experimentally observed high torquoselectivities and complete diastereoselectivities of the 8pi-electrocyclization products have been thoroughly studied using density functional computations at B3PW91/6-31G(d,p). The different P- and M-helical topologies for the Mobius aromatic transition structures are the origin of the observed torquoselectivities in the cyclooctatrienes. The P-helical topologies direct the newly formed single bonds into a favorable equatorial position of the neighboring cycloalkane moieties (X = ring size) that retain their most stable conformation. The M-helical transition structures lead to an axial connection for the smaller rings (X = 4-6) and an equatorial connection for the seven- and eight-membered cycloalkanes. This leads to unfavorable conformations for the larger cycloalkane moieties. Experiments and computations show that for trienynes involving small neighboring cycloalkane groups (X = 4-6) M-helical topology is preferred toward cyclooctatrienes and in the following the corresponding fenestradienes can be formed as kinetic or even thermodynamic products; they convert to their more stable cyclooctatriene valence isomers derived from P-helical transition structures at higher temperatures. For larger cycloalkane moieties with more conformational flexibility only cyclooctatrienes with torquoselectivities derived from P-helical transition structures form.

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Section: Introductionmentioning

confidence: 99%

Understanding the Torquoselectivity in 8π-Electrocyclic Cascade Reactions: Synthesis of Fenestradienes versus Cyclooctatrienes

et al. 2009

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“…Apparently trans -bridging a butadiene 1,2 on a cyclobutane ring, with the latter’s freedom to pucker, is not as difficult as one might think . Nor is it problematic for a butadiene to bridge the gauche positions of an approximately staggered ethane.…”

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confidence: 99%

Jailbreaking Benzene Dimers

2012

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We suggest four new benzene dimers, (C(6)H(6))(2), all featuring one or more cyclohexadiene rings trans-fused to 4- or 6-membered rings. These hypothetical dimers are 50-99 kcal/mol less stable than two benzenes, but have computed activation energies to fragmentation ≥27 kcal/mol. A thorough search of potential escape routes was undertaken, through cyclobutane ring cleavage to 12-annulenes, sigmatropic 1,5-H-shifts, electrocyclic ring-openings of the 6-membered rings, and Diels-Alder dimerizations. Some channels for reaction emerge, but there is a reasonable chance that some of these new benzene dimers can be made.

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Time‐dependent density functional theory study on hydrogen‐bonded intramolecular charge‐transfer excited state of 4‐dimethylamino‐benzonitrile in methanol

2008

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The time-dependent density functional theory (TDDFT) method was carried out to investigate the hydrogen-bonded intramolecular charge-transfer (ICT) excited state of 4-dimethylaminobenzonitrile (DMABN) in methanol (MeOH) solvent. We demonstrated that the intermolecular hydrogen bond C[triple bond]N...H-O formed between DMABN and MeOH can induce the C[triple bond]N stretching mode shift to the blue in both the ground state and the twisted intramolecular charge-transfer (TICT) state of DMABN. Therefore, the two components at 2091 and 2109 cm(-1) observed in the time-resolved infrared (TRIR) absorption spectra of DMABN in MeOH solvent were reassigned in this work. The hydrogen-bonded TICT state should correspond to the blue-side component at 2109 cm(-1), whereas not the red-side component at 2091 cm(-1) designated in the previous study. It was also demonstrated that the intermolecular hydrogen bond C[triple bond]N...H-O is significantly strengthened in the TICT state. The intermolecular hydrogen bond strengthening in the TICT state can facilitate the deactivation of the excited state via internal conversion (IC), and thus account for the fluorescence quenching of DMABN in protic solvents. Furthermore, the dynamic equilibrium of these electronically excited states is explained by the hydrogen bond strengthening in the TICT state.

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A computational investigation on the sequential rearrangement mechanism of 2‐allyl‐2,4,5‐hexatrienaldehyde involving [1,5]‐hydrogen migration and 8π‐electrocyclization

Cited by 5 publications

References 41 publications

Understanding the Torquoselectivity in 8π-Electrocyclic Cascade Reactions: Synthesis of Fenestradienes versus Cyclooctatrienes

Understanding the Torquoselectivity in 8π-Electrocyclic Cascade Reactions: Synthesis of Fenestradienes versus Cyclooctatrienes

Jailbreaking Benzene Dimers

Time‐dependent density functional theory study on hydrogen‐bonded intramolecular charge‐transfer excited state of 4‐dimethylamino‐benzonitrile in methanol

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