Chirality as a probe for the structure of 1,2-cycloheptadiene and 1,2-cyclohexadiene

Balcı, Metin; Jones, W. M.

doi:10.1021/ja00545a057

Cited by 138 publications

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“…Consistent with this result is a calculated [18] barrier to racemization of S0.1 kcal tool -I (Section II.C) corresponding to a bent, planar allene singlet diradical as the transition state. Balci and Jones [84] have recently demonstrated that bending in highly strained, cyclic allenes,…”

Section: Planar Allenesmentioning

confidence: 99%

Reactive intermediates in the interconversions of C3H4 hydrocarbons

1984

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Section: Planar Allenesmentioning

confidence: 99%

Reactive intermediates in the interconversions of C3H4 hydrocarbons

1984

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“…Compared to 1,2-cyclohexadiene, the chirality and [2 ϩ 4] cycloadditions. Whereas 3 is generated by of which is supported by experiment, [15] the smaller length β-elimination of hydrogen bromide from the corresponding of the tether across the allene termini and the extension of vinyl bromides, [10] dihalocarbene adducts of cyclopenthe allyl to a pentadienyl radical moiety enforce the planar tether, defined as the sum of the lengths of the four bonds (standard bond lengths), is only 5 pm larger than in 1. Additionally, the participation of a lone electron pair of the oxygen atom, as depicted by formula 4c, could cause a stabilization similar to the delocalization energy of the π electron in 1b.…”

mentioning

confidence: 99%

3δ2-Chromene (2,3-Didehydro-2H-1-benzopyran): Generation and Interception

Christl¹,

Drinkuth

1998

Eur. J. Org. Chem.

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The treatment of 3‐bromo‐2H‐chromene (7), dissolved in furan, 2‐methylfuran, or 2,5‐dimethylfuran, with potassium tert‐butoxide, leads to formation of the epoxybenzo[c]chromene derivatives 8−11 in yields of 28−59%. Likewise, in styrene solution, exo‐2‐phenylcyclobuta[b]chromene 12 is produced (41% yield). With tetrahydrofuran as the solvent, 2‐tert‐butoxy‐2H‐chromene (13) is observed as the only product (79% yield). From these results, it is concluded that 7 is converted by β‐elimination into the title compound 5. This reactive intermediate is then intercepted by the furans and styrene in cycloaddition reactions to give compounds 8−12, whereas reaction with KOtBu/HOtBu transforms it to the acetal 13. The epoxybenzochromenes 8, 9, and 11 rearrange on heating at 110°C to give the epoxyxanthene derivatives 16−18.

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“…By elegant experiments, Balci and Jones [1,2] established the chirality of the six-membered cyclic allenes [3] 1,2-cyclohexadiene and bicyclo[3.2.1]octa-2,3,6-triene. Later, quan-these results, a model is proposed for the steric course of the reaction sequence, leading from a pure enantiomer 1 to the 70:30 mixtures of the product enantiomers 6.…”

Section: Introductionmentioning

confidence: 99%

The Stereochemical Course of the Generation and Interception of aSix‐Membered Cyclic Allene: 3δ²‐1H‐Naphthalene (2,3‐Didehydro‐1,2‐dihydronaphthalene)

et al. 2006

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Keywords: CD spectra / Cycloadditions / Cyclic allenes / Enantioselectivity / Quantum chemistry calculationsThe bromofluorocarbene adduct rac-1 of indene, possessing the fluorine atom at the endo position, is a useful substrate for the generation of the isonaphthalene 4 by the DoeringMoore-Skattebøl reaction. By resolution of rac-1, an enantiomerically pure precursor of a six-membered cyclic allene was obtained for the first time. The treatment of (+)-or (-)-1, dissolved in 2,5-dimethyl-, 2-tert-butyl-5-methyl-, or 2,5-bis-(tert-butyl)furan, with methyllithium gave rise to the [4+2] cycloadducts 6 of 4 to the furans. It was shown by means of HPLC on Chiralcel OD that the formation of 6 proceeded with about 40 % ee, and that this value was independent of the type and concentration of the furan, and the reaction temperature. The absolute configurations of the enantiomers 1, as well as those of the enantiomers 6, were determined by simulation of the CD spectra by quantum chemical methods and by the comparison of them with the experimental spectra. In the case of (+)-1, the reliability of this procedure was checked by X-ray crystal structure analysis. On the basis of

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Chirality as a probe for the structure of 1,2-cycloheptadiene and 1,2-cyclohexadiene

Cited by 138 publications

References 0 publications

Reactive intermediates in the interconversions of C3H4 hydrocarbons

Reactive intermediates in the interconversions of C3H4 hydrocarbons

3δ2-Chromene (2,3-Didehydro-2H-1-benzopyran): Generation and Interception

The Stereochemical Course of the Generation and Interception of aSix‐Membered Cyclic Allene: 3δ²‐1H‐Naphthalene (2,3‐Didehydro‐1,2‐dihydronaphthalene)

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Chirality as a probe for the structure of 1,2-cycloheptadiene and 1,2-cyclohexadiene

Cited by 138 publications

References 0 publications

Reactive intermediates in the interconversions of C3H4 hydrocarbons

Reactive intermediates in the interconversions of C3H4 hydrocarbons

3δ2-Chromene (2,3-Didehydro-2H-1-benzopyran): Generation and Interception

The Stereochemical Course of the Generation and Interception of aSix‐Membered Cyclic Allene: 3δ2‐1H‐Naphthalene (2,3‐Didehydro‐1,2‐dihydronaphthalene)

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The Stereochemical Course of the Generation and Interception of aSix‐Membered Cyclic Allene: 3δ²‐1H‐Naphthalene (2,3‐Didehydro‐1,2‐dihydronaphthalene)