Solid state and theoretical evaluation of β-fluoroethyl esters indicate a fluorine-ester gauche effect

Briggs, Caroline R.S.; O’Hagan, David; Rzepa, Henry; Slawin, Alexandra M. Z.

doi:10.1016/j.jfluchem.2003.08.011

Cited by 28 publications

(5 citation statements)

References 11 publications

(23 reference statements)

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“…251,252 Although X and Y are usually F or O, the choice of the second substituent Y is quite broad in fluoroethanes, X = F 253. The gauche effect is useful for control of chemical structure and reactivity 254–257. For example, the gauche effect has been utilized to achieve efficient and ‘strain‐free’ conformational control in the elusive 5‐endo‐dig cyclization of carbon‐centered radicals 258…”

Section: Examples/stereoelectronic Effectsmentioning

confidence: 99%

Hyperconjugation

Alabugin

Gilmore

Peterson

2011

WIREs Comput Mol Sci

285

289

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This review outlines the ubiquitous nature of hyperconjugative interactions and their role in the structure and reactivity of organic molecules. After defining the common hyperconjugative patterns, we discuss the main factors controlling the magnitude of hyperconjugative effects, including orbital symmetry, energy gap, electronegativity, and polarizibility. The danger of underestimating the magnitude of hyperconjugative interactions are illustrated by a number of spectroscopic, conformational, and structural effects. Through the use of advanced computational techniques, the true role of hyperconjugative effects, as it pertains to their influence on stereoelectronics, conformational equilibria, and reactivities relative to other electronic effects, continue to be uncovered.

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Section: Examples/stereoelectronic Effectsmentioning

confidence: 99%

Hyperconjugation

Alabugin

Gilmore

Peterson

2011

WIREs Comput Mol Sci

285

289

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“…For example, compounds containing F–C–C–O and F–C–C–N also experience this effect ( 12 – 15 , Fig. 1 ) [ 9 , 11 – 13 ]. In general, more electronegative substituents give rise to stronger gauche effects.…”

Section: Reviewmentioning

confidence: 99%

The C–F bond as a conformational tool in organic and biological chemistry

Hunter¹

2010

Beilstein J. Org. Chem.

325

173

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SummaryOrganofluorine compounds are widely used in many different applications, ranging from pharmaceuticals and agrochemicals to advanced materials and polymers. It has been recognised for many years that fluorine substitution can confer useful molecular properties such as enhanced stability and hydrophobicity. Another impact of fluorine substitution is to influence the conformations of organic molecules. The stereoselective introduction of fluorine atoms can therefore be exploited as a conformational tool for the synthesis of shape-controlled functional molecules. This review will begin by describing some general aspects of the C–F bond and the various conformational effects associated with C–F bonds (i.e. dipole–dipole interactions, charge–dipole interactions and hyperconjugation). Examples of functional molecules that exploit these conformational effects will then be presented, drawing from a diverse range of molecules including pharmaceuticals, organocatalysts, liquid crystals and peptides.

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“…7 This nding was in accord with an earlier explanation of the gauche effect in various compounds as a prevailing nucleus-electron attraction over nucleus-nucleus and electron-electron repulsion. 4 The uorine gauche effect was found experimentally and/or theoretically in various other compounds having an electronegative substituent in b-position to the uorine atom, such as O-b-uoroethyl esters, 8 N-b-uoroethylamides, 9 1-uoro-2-nitroethane, 10 1-azido-2-uoroethane, 10 1-uoro-2-iso(thio) cyanatoethane, 10 2-uoroimines, 11 2-uoroethanol 12 and 2-uoroethylamine. 12e,13 Its origin is commonly ascribed to stereoelectronic effects, that is, the stabilizing hyperconjugative interactions wherein s * C-F and s * C-X orbitals (X ¼ electronegative atom in b-position to F) act as acceptors of electron density donated from antiperiplanar s C-H bonds in gauche forms.…”

Section: Introductionmentioning

confidence: 99%