NMR Study on 1,2,4,5-Tetrasubstituted 3,3,6,6-Tetradeuterated Cyclohexanes: Conformational Contributions and 1,3-Diaxial and Vicinal Deshielding Effects of Amino and Alkylated Amino Groups and Their Protonated Forms

Whelton, Bartlett D.; Carr, J. B.; Lowry, Betty R.; Huitric, Alain C.

doi:10.1002/jps.2600620505

Cited by 5 publications

(9 citation statements)

References 18 publications

(12 reference statements)

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“…This dramatic change, which exceeded 10 kJ/mol in terms of the relative conformational stability, was attributed to destruction of the stabilizing intramolecular OH⋅⋅⋅N hydrogen bond in 25A by the hydrogen bond acceptor solvents [18]. Similar results were obtained earlier for trans-2-o-tolyl-cis -4-hydroxy (amino) -trans-5-amino (hydroxy) cyclohexanols [51] and some other trans-2-aminocyclohexanols [52]. Thus, the trans-2-aminocyclohexanol moiety provides a promising type of a rapid conformational lock/ trigger.…”

Section: Hydrogen Bond Locks and Ph-induced Conformational Switchessupporting

confidence: 84%

“…trans-1,2-Cyclohexanediol and trans-2-aminocyclohexanols are well known to strongly prefer the diequatorial conformation, in part due to intramolecular hydrogen bonding between vicinal substituents [18,38,[51][52][53]. These structural moieties can be used as conformational counterbalances or locks.…”

Section: Hydrogen Bond Locks and Ph-induced Conformational Switchesmentioning

confidence: 99%

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Cyclohexane-Based Conformationally Controlled Crowns and Podands

Samoshin¹

2005

MROC

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Section: Hydrogen Bond Locks and Ph-induced Conformational Switchessupporting

confidence: 84%

Section: Hydrogen Bond Locks and Ph-induced Conformational Switchesmentioning

confidence: 99%

Cyclohexane-Based Conformationally Controlled Crowns and Podands

Samoshin¹

2005

MROC

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“…This dramatic change, which exceeded 10 kJ/mol in terms of the relative conformational stability, was attributed to destruction of the stabilizing intramolecular OH⋅⋅⋅N hydrogen bond in 2A by the hydrogen bond acceptor solvents. 20 Similar results were obtained 39 and some 5-alkyl-trans-2-aminocyclohexanols. 40 Thus, the trans-2-aminocyclohexanol moiety provides a promising type of a rapid conformational trigger.…”

Section: Methodssupporting

confidence: 76%

“…trans-1,2-Cyclohexanediols and trans-2-aminocyclohexanols are well known to strongly prefer the diequatorial conformation, in part due to an intramolecular hydrogen bonding between vicinal substituents. 20,23,[39][40][41][42] Therefore, these structural moieties can be used as conformational counterbalances or locks.…”

Section: Methodsmentioning

confidence: 99%

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Trans-2-aminocyclohexanols as pH-triggered molecular switches

Brazdova¹,

Koo²,

Wong³

et al. 2005

Arkivoc

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Cyclohexane-based conformationally controlled ionophores, the emerging new class of molecular switches, provide a new and promising approach to allosteric systems with negative cooperativity. Protonation of trans-2-aminocyclohexanols leads to dramatic conformational changes: due to an intramolecular hydrogen bond, a conformer with equatorial position of ammonio-and hydroxy-groups becomes predominant. Thus, these structures can serve as powerful conformational pH-triggers. The trans-2-aminocyclohexanol moiety has been used for pH-triggered conformational switching of a crown ether and a podand, and their complexes with potassium ion.

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Trans‐2‐Aminocyclohexanol derivatives as pH‐triggered conformational switches

Samoshin

Zheng

Liu

2017

J of Physical Organic Chem

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A series of trans-2-aminocyclohexanol derivatives have been explored as powerful conformational pH triggers. On protonation of the amino group, a conformer with equatorial position of ammonio and hydroxy groups becomes predominant because of an intramolecular hydrogen bond and electrostatic interactions. The energy of these interactions was estimated to be above 10 kJ/mol and in some models exceeded 20 kJ/mol (strong enough to twist a ring in tert-butyl derivatives). As a result of this conformational flip, all other substituents are forced to change their orientation. If the substituents are designed to perform certain geometry-dependent functions, for example, as cation chelators or as lipid tails, such acid-induced transition may be used to control the corresponding molecular properties. The pH sensitivity of conformational equilibria was explored by 1 H nuclear magnetic resonance spectroscopy (NMR), and the titration curves were used for estimation of the pK a values of protonated compounds that varied from 2.6 to 8.5 (in d 4 -methanol) depending on the structure of amino group. Thus, trans-2-aminocyclohexanols can be also used as conformational pH indicators in organic solvents.

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NMR Study on 1,2,4,5-Tetrasubstituted 3,3,6,6-Tetradeuterated Cyclohexanes: Conformational Contributions and 1,3-Diaxial and Vicinal Deshielding Effects of Amino and Alkylated Amino Groups and Their Protonated Forms

Cited by 5 publications

References 18 publications

Cyclohexane-Based Conformationally Controlled Crowns and Podands

Cyclohexane-Based Conformationally Controlled Crowns and Podands

Trans-2-aminocyclohexanols as pH-triggered molecular switches

Trans‐2‐Aminocyclohexanol derivatives as pH‐triggered conformational switches

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