The effect of polar substituents on the solvolysis of secondary and tertiary 2-norbornyl derivatives.

Lenoir, Dieter; Roll, William D.; Weiss, Erika R.; Wenke, G.

doi:10.1016/s0040-4039(00)78098-1

Cited by 4 publications

References 13 publications

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Carbon Participation in the Solvolysis of 6‐exo‐substituted 2‐exo‐ and 2‐endo‐Norbornyl p‐Toluenesulfonates. Norbornanes part 5

Fischer

Grob

Hanreich

et al. 1981

Helvetica Chimica Acta

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The solvolysis rates and products of the 6‐exo‐substituted 2‐exo‐ 1a‐1u, and 2‐endo‐norbornyl p‐toluenesulfonates 2a‐2u, have been determined. In general, the rate constants for 1 and 2 (log k) correlate well with the inductive constants σ Iq of the substitutents at C(6); however, their sensitivity to σ Iq is much larger in the 2‐exo‐series 1 than in the 2‐endo‐series 2. This differential transmission of polar effects is the cause of decreasing 2‐exo/2‐endo rate ratios from 2388 for R = t‐C4H9 to 0.37 for R = Br, i. e. with increasing electron attraction by the substituent. The high sensitivity of the rate constants for the 2‐exo‐p‐toluenesulfonates 1 to σ Iq indicates an unusually strong inductive interaction between C(6) and the incipient cationic center at C(2). This interaction is ascribed to the participation of the pentacoordinate C(6)‐atom, i. e. to 1,3‐bridging, a consequence of steric hindrance of nucleophilic solvent participation in norbornanes. Donor substituents enhance 1,3‐bridging, lead to faster reactions and to the formation of 2‐exo substitution products. Conversely, acceptor substituents reduce 1,3‐bridging, decrease rates and facilitate the formation of 2‐endo substitution products. Graded 1,3‐bridging is discussed in the light of Winstein's nonclassical ion concept.

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Carbon Participation in the Solvolysis of 6‐exo‐substituted 2‐exo‐ and 2‐endo‐Norbornyl p‐Toluenesulfonates. Norbornanes part 5

Fischer

Grob

Hanreich

et al. 1981

Helvetica Chimica Acta

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Norbornanes. Part 18. Inductive Charge Dispersal in the Solvolyses of 4‐ and 5‐Substituted 2‐Norbornyl p‐Toluenesulfonates

Fuso

Grob

Sawlewicz

et al. 1986

Helvetica Chimica Acta

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The solvolysis rates and products of 4‐ and 5‐exo‐substituted 2‐exo‐ and 2‐endo‐norbornyl tosylates 9 and 10, respectively, are reported. The logarithms of the rate constants (log k) correlate linearly with the inductive constants σ Iq for the substituents. A comparison of the reaction constants p1 for the 4‐, 5‐, 6‐, and 7‐substituted 2‐exo‐ and 2‐endo‐tosylates 9, 10, 1, and 2 respectively, indicates that inductivity is higher for 2‐exo‐ionization than for 2‐endo‐ionization in all series. This observation is attributed to the more favorable alignment of neighbouring C‐atoms for dorsal participation in exo‐ionization, especially, in the case of C(6).

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Long range electrical field effects in solvolysis and ¹³C‐NMR shielding of androstanes with halogen, hydroxy and oxo substituents

Schneider

Becker

1989

J of Physical Organic Chem

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The solvolysis of 21 different 3‐ or 17‐androstanyl tosylates or chlorides with halogen, hydroxy or oxo substituents in 17‐ or 3‐position shows rate constant variations in hexafluoro isopropanol of up to 6·3 with regular differences for epimeric substituents. Similar variations ae seen over a distance of ∼10 Å in 13C‐NMR shifts at C‐17‐ones of androstan‐17‐ones with varied halogen substituents in C‐3, whereas the shielding observed at other distant carbon atoms excludes significant through bond effects. It is shown how, on the basis of suitable Coulomb‐type equations and of force field minimized geometries, both the stability variation of carbocationic transition states and the carbonyl group polarization are predictable by linear electric field effects, using the same parametrization.

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The effect of polar substituents on the solvolysis of secondary and tertiary 2-norbornyl derivatives.

Cited by 4 publications

References 13 publications

Carbon Participation in the Solvolysis of 6‐exo‐substituted 2‐exo‐ and 2‐endo‐Norbornyl p‐Toluenesulfonates. Norbornanes part 5

Carbon Participation in the Solvolysis of 6‐exo‐substituted 2‐exo‐ and 2‐endo‐Norbornyl p‐Toluenesulfonates. Norbornanes part 5

Norbornanes. Part 18. Inductive Charge Dispersal in the Solvolyses of 4‐ and 5‐Substituted 2‐Norbornyl p‐Toluenesulfonates

Long range electrical field effects in solvolysis and ¹³C‐NMR shielding of androstanes with halogen, hydroxy and oxo substituents

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The effect of polar substituents on the solvolysis of secondary and tertiary 2-norbornyl derivatives.

Cited by 4 publications

References 13 publications

Carbon Participation in the Solvolysis of 6‐exo‐substituted 2‐exo‐ and 2‐endo‐Norbornyl p‐Toluenesulfonates. Norbornanes part 5

Carbon Participation in the Solvolysis of 6‐exo‐substituted 2‐exo‐ and 2‐endo‐Norbornyl p‐Toluenesulfonates. Norbornanes part 5

Norbornanes. Part 18. Inductive Charge Dispersal in the Solvolyses of 4‐ and 5‐Substituted 2‐Norbornyl p‐Toluenesulfonates

Long range electrical field effects in solvolysis and 13C‐NMR shielding of androstanes with halogen, hydroxy and oxo substituents

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Long range electrical field effects in solvolysis and ¹³C‐NMR shielding of androstanes with halogen, hydroxy and oxo substituents