An octahydrodimethanonaphthyl non-classical homocyclopropenyl cation

Winstein, S.; Hansen, Robert L.

doi:10.1016/s0040-4039(01)99385-2

Cited by 10 publications

(7 citation statements)

References 11 publications

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“…All the pentane washings and extracts were combined, washed with water, dried (Na2S04), and concentrated. The residual white solid was sublimed at 80°( 1 mm) to give 9.0 g (41% from the crude diene) of solid, mp 94-96°( lit.7 mp 90-92), that was 99.3% endo.endo diene and 0.7% endo.endo monoene (gc analysis on a 25% SE-30 on Chromosorb W colunn26): ir (CC14) 3.21 (w), 3.30 (m), 3.41 (s), 3.52 (m), 6.39 (w), 6.90 (m), 7.49 (s), 7.88 (w), 8.00 (s), 8.11 (w), 8.20 (w), 8.85 (m), 9.12, (w), 9.71 (w), 10.13 (w), 10.35 (w), 10.99 (s), 11.31 (a), 11.45 (s), 14.00 (vs), 14.50 µ (w).…”

Section: Methodsmentioning

confidence: 99%

Formation of endo acetate in acetolysis of a fused endo-norbornyl brosylate via C-7 participation

Howe¹,

Winstein²

1973

J. Org. Chem.

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Section: Methodsmentioning

confidence: 99%

Formation of endo acetate in acetolysis of a fused endo-norbornyl brosylate via C-7 participation

Howe¹,

Winstein²

1973

J. Org. Chem.

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“…NMR data suggest that the ~r system is somewhat polar, i.e. it may have partial homocyclopropenyl carbocation character (Winstein & Hansen, 1960), as in structure (7). The C(9)...C(12)oand C(10)-.. C(12) distances [2.946 (2) and 2.977 (2) A, respectively] are consistent with 7r-~r repulsion in (1), which would be mitigated by electron transfer from the C(9~C(10) double bond towards C(13).…”

Section: Analysis Of Least-squares Planes and Torsion Angles Showed Tmentioning

confidence: 99%

Pyramidalization in a tetracyclic perpendicular diene derivative

Lloyd¹,

Arif²,

Allred³

1992

Acta Crystallogr C

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“…This material was used directly without purification. 9,9-Dichloro-exo-~eiitacyclo[5.4.0.02~6.03~'1.08~10] undecan-4-01 (13). To a stirred susperision of lithium aluminum hydride (120 mg) in 10 mL of anhydrous ether was added dropwise a solution of 12 (700 mg) in 10 mL of the same solvent.…”

Section: Endo-tetracyclo[ 53002~603j0]de~-4-en-8-ol (5a)mentioning

confidence: 99%

Impact of high-lying .sigma. orbitals and extensive through-bond interaction on chemical reactivity. 2. Solvolytic studies of hypostrophene derivatives

Klein¹,

Paquette²

1978

J. Org. Chem.

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Acetolysis of exo-and endo-tetracyclo[5.3.0.0z~6.03~10]decan-4-yl tosylates (6b and 8b) in buffered HOAc a t 71 "C produced 16b (together with 2% of 6c in the endo case), but a t rates estimated to differ by a factor of 170 (with 6b faster). Comparable solvolysis of the unsaturated exo tosylate 3b (at 25.9 "C) led rapidly to 18b (50%), 19a (5%), and 19b (4,5%j, a product distribution quite unlike that obtained from its endo epimer 5b (18b accompanied by some polymer formation). These findings demonstrate that the frequently observed ability of a proximate double bond to engage in transannular participation has been overridden by lateral u-bond participation. The kinetic and product data suggest that the first cation emanating from 5b is classical, while that from 3b is generated with anchimeric assistance and characterized by u delocalization. Whereas acetolysis (71 "C) of em-cyclopropyl derivative 10b returned only 20a, its endo counterpart 15b gave a complex acetate product mixture a t a rate approximately 440 times slower. The involvement of neighboring-group participation could again be implicated for lob, since interaction 01' the cationic center with the cyclopropane ring is effectively repressed. The rate constants and product distributioiis provide convincing demonstration of the effectiveness with which such anchimeric assistance can accelerate and control the ultimate outcome of cationic rearrangements.Interest in hypostrophene (tetracyclo[5.3.0.0.2~6.03Jo]-deca-4,8-diene (l))l-:] derives chiefly from its structural features, including its Czu symmetry, the overriding by through-bond coupling of direct through-space Z-z interact i~n ,~ and its obvious strain energy. The primary determinants of the observed level ordering in 1 are its exceptionally high-1 -, 2 Y lying lateral u orbitals and their geometric relationship to the T bonds. Such symmetry-enforced indirect interaction between the double bonds should have significant consequences on chemical reactivity. This conclusion has received qualitative support from the response of 1 to attack by electrophilic reagents.lJ Hoffmann, Mollgre, and Heilbronner have previously presented arguments supporting the notion that the exceptional unreactivity of 7-norbornyl cation precursors (2) is due not to the change in angle strain accompanying their ionization,6 but to destabiiization brought on by the inability of proper ribbon orbitals to interact suitably with the carbonium ion center.7 This lack of interaction causes 2 to be less stable and more difficult to generate than it should otherwise be. At issue is whether similar phenomena would be observed in carbonium ions derived from 1 and allied structures.The recent availability of efficient routes to 1 and the knowledge that carbocations are particularly sensitive to prevailing orbital interactions prompted a detailed kinetic study of the solvolytic behavior of a number of hypostrophene derivatives. In particular, a series of e m -and endo-p-toluenesulfonate esters have been prepared in which the transannular...

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An octahydrodimethanonaphthyl non-classical homocyclopropenyl cation

Cited by 10 publications

References 11 publications

Formation of endo acetate in acetolysis of a fused endo-norbornyl brosylate via C-7 participation

Formation of endo acetate in acetolysis of a fused endo-norbornyl brosylate via C-7 participation

Pyramidalization in a tetracyclic perpendicular diene derivative

Impact of high-lying .sigma. orbitals and extensive through-bond interaction on chemical reactivity. 2. Solvolytic studies of hypostrophene derivatives

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