Synthesis and solvolysis of 4-substituted nortricyclenes

Chenier, Philip J.; McClure, James R.; Golembeski, David J.

doi:10.1021/jo00416a012

Cited by 3 publications

(1 citation statement)

References 5 publications

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“…Three possible explanations for the astonishingly high k values of 9 were considered: (a) relief of F-strain 24 due to steric congestion in the ground state of 9 , (b) edge-bridging of the cyclopropyl group leading to a (distorted) bicyclobutonium cation,1d and (c) the increasing electron demand generated by the destabilizing effect ,, of the (nearly) perpendicular cyclopropyl group, which enhances the participation of the σ-bonds of the norbornane framework.…”

Section: Resultsmentioning

confidence: 99%

An Experimental and Computational Study about the Effect of a Spirocyclopropane Group on the Solvolysis Rates of Bridgehead Triflates

Cerero

et al. 1999

J. Org. Chem.

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7',7'-Dimethylspiro[cyclopropane-1,2'-norbornan]-1'-yl triflate (9) was obtained and its solvolysis rates in buffered 60% aqueous ethanol were determined at different temperatures. The solvolytic behavior of 9 and other bridgehead derivatives (13-17, see Table 1) was studied by force-field, semiempirical and ab initio [B3LYP/6-31g(d)] methods. Cation 9(+) is a slightly pyramidal cyclopropylcarbinyl cation in a nearly perpendicular conformation, showing an sp(2)-like hybridization. Its high electron demand provokes an enhancement of the sigma-participation of the C(5)-C(6) and C(4)-C(7) bonds. The introduction of a cyclopropyl group adjacent to the bridgehead cation leads to an increase of the strain energy. This fact has two opposite effects on the solvolysis rate: (a) the strain energy hinders the flattening of the cation and, hence, originates a rate depression, and (b) the strained C-C bonds are prone to stabilize the cation at C(1) by sigma-delocalization, which provokes a rise of the solvolysis rate. Both effects are accounted for only by the B3LYP/6-31g method. The claimed electron-withdrawal effect of the cyclopropyl group as a basis for the small k(17)/k(16) rate ratio is not confirmed by our calculations.

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Section: Resultsmentioning

confidence: 99%

An Experimental and Computational Study about the Effect of a Spirocyclopropane Group on the Solvolysis Rates of Bridgehead Triflates

Cerero

et al. 1999

J. Org. Chem.

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ChemInform Abstract: SYNTHESIS AND SOLVOLYSIS OF 4‐SUBSTITUTED NORTRICYCLENES

Chenier¹,

McClure²,

Golembeski³

1979

Chemischer Informationsdienst

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Norbornanes. Part 19. The Inductive Model for Norbornyl Cation Formation

Altmann-Schaffner

Grob

1987

Helvetica Chimica Acta

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Two CH, groups at C(6) of 2-exo-(10a) and 2-endo-norbornyl p-toluenesulfonate l l a lower their solvolysis rates in 80% EtOH by factors of 28 and 16, respectively. A spirocyclopropyl group including C(6), as in 21s and 22a. reduces the rate ofexo-and endo-ionization by factors of 250 and 8, respectively. The geminally dimethyl-substituted tosylates 10a and l l a yield the 2-em-alcohol lob, whereas the spirocyclopropyl-substituted tosylates 21a and 22a furnish rearranged 3-brendanol 23. These findings are readily rationalized by the inductive model, according to which norbornyl cation formation is controlled by the inductive effect of dorsal substituents.Substituents at C(4), C(5), C(6), and C(7) of 2-exo-and 2-endo-norbornyl p-toluenesulfonate (tosylate) 1 and 2, respectively, control solvolysis rates by their inductive (I) effect only [ 11. This follows from the observed linear correlation of the logarithms of the rate constant logk with the inductive constants of the substituents CT: [2] at these positions according to the equation log k/ko = ploy, which, in addition to other data [3], precludes steric effects as a significant rate and product-controlling factor'). 7

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Synthesis and solvolysis of 4-substituted nortricyclenes

Cited by 3 publications

References 5 publications

An Experimental and Computational Study about the Effect of a Spirocyclopropane Group on the Solvolysis Rates of Bridgehead Triflates

An Experimental and Computational Study about the Effect of a Spirocyclopropane Group on the Solvolysis Rates of Bridgehead Triflates

ChemInform Abstract: SYNTHESIS AND SOLVOLYSIS OF 4‐SUBSTITUTED NORTRICYCLENES

Norbornanes. Part 19. The Inductive Model for Norbornyl Cation Formation

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