trans-2-Aminocyclohexanols as pH-triggers for conformationally controlled crowns and podands

Samoshin, Vyacheslav V.; Чертков, В. А.; Gremyachinskiy, Dmitriy; Dobretsova, E. K.; Шестакова, А. К.; Vatlina, L. P.

doi:10.1016/j.tetlet.2004.09.004

Cited by 22 publications

(43 citation statements)

References 16 publications

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“…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%

“…As we suggested in a preliminary publication, 23 another way to control such a conformational equilibrium is an addition of acid to protonate the amino group, and to generate a stronger intramolecular hydrogen bond of O⋅⋅⋅H-N + type, 23,39 e.g. in 3A (Scheme 3).…”

Section: Earlier For Trans-2-o-tolyl-cis-4-hydroxy(amino)-trans-5-amimentioning

confidence: 99%

“…in 3A (Scheme 3). 23 This bond would stabilize conformation 3A, thus moving the ester groups away from each other, and decreasing their potential ability to interact with another molecule or ion, for example to form complexes like 1B. …”

Section: Earlier For Trans-2-o-tolyl-cis-4-hydroxy(amino)-trans-5-amimentioning

confidence: 99%

“…Conformational control via introduction of various substituent(s) into a trans-fused six-membered cycle was proposed by us as a new principle for modification of the complexing ability of (cyclohexano)crown compounds and non-macrocyclic ionophores (podands). [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Similar ideas were suggested for cyclohexanebased podands by Raban et al [24][25][26][27] In these structures, a substituent plays a role of 'conformational lever', or 'counterbalance', and the cyclohexane moiety serves as a mechanical transmitter. The cyclohexane machinery can also mimic an allosteric effect by transmitting a conformational change (signal) from one complexing center (e.g.…”

Section: Introductionmentioning

confidence: 97%

“…a macroheterocycle or podand) to another site, which results in an externally controlled conformational equilibrium of the type 1A 1B (Scheme 1). 16,[19][20][21]23 A change by external influence of non-bonded interactions between groups W and Z (and/or X and Y) in structures 1 will change the relative stability of conformers. By affecting these interactions one can control the position of conformational equilibrium of the type 1A 1B, thus controlling the shape and the complexing ability of the macrocycle or podand.…”

Section: Introductionmentioning

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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Section: Methodsmentioning

confidence: 99%

Section: Earlier For Trans-2-o-tolyl-cis-4-hydroxy(amino)-trans-5-amimentioning

confidence: 99%

Section: Earlier For Trans-2-o-tolyl-cis-4-hydroxy(amino)-trans-5-amimentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Trans-2-aminocyclohexanols as pH-triggered molecular switches

Brazdova¹,

Koo²,

Wong³

et al. 2005

Arkivoc

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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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Exploration of trans‐2‐(azaarylsulfanyl)‐cyclohexanols as potential pH‐triggered conformational switches

Ruyonga

Mendoza

Browne

et al. 2020

J of Physical Organic Chem

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A series of trans‐2‐(azaarylsulfanyl)‐cyclohexanols, structurally similar to previously studied trans‐2‐aminocylohexanols, have been synthesized and explored as conformational pH triggers. 1H NMR spectroscopy was used to estimate the position of the chair‐chair conformational equilibrium and its acid‐induced shift towards the conformer with the azaarylsulfanyl and hydroxy groups in equatorial positions due to an intramolecular hydrogen bond and electrostatic interactions. Such acid‐induced transition may be used to control the geometry‐dependent molecular properties. The 1H NMR titration curves were used for estimation of the pKa values of protonated compounds that varied from 2.8 to 4.3 (in d4‐methanol) depending on the structure of the azaarylsulfanyl group.

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trans-2-Aminocyclohexanols as pH-triggers for conformationally controlled crowns and podands

Cited by 22 publications

References 16 publications

Trans-2-aminocyclohexanols as pH-triggered molecular switches

Trans-2-aminocyclohexanols as pH-triggered molecular switches

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

Exploration of trans‐2‐(azaarylsulfanyl)‐cyclohexanols as potential pH‐triggered conformational switches

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