Trans-1,2-Cyclohexanedicarboxylic acid derivatives as pH-trigger for conformationally controlled crowns

Trans-2-aminocyclohexanols as pH-triggered molecular switches

“…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.…”

“…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.…”

“…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.…”

“…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.…”

Synthesis, Conformational Studies and Mannosidase Stability of a Mimic of 1,2‐Mannobioside

“…A mimic of the 1,2-mannobioside 1 was prepared by replacing the reducing-end mannose unit with the carbocyclic diol 2 [(1S,2S,4S,5S)-dicarboxycyclohexane diol, DCCHD; Figure 1], [4] a conformationally stable 1,2 trans-diaxial diol. [4,11] Computer-aided molecular design (see below) suggested that 2 can be used as a mimic of the 2-substituted α-mannose unit in 1 without altering the overall shape of the molecule and therefore the presentation of the terminal (non-reducing end) residue. NMR studies confirmed that the resulting pseudo-mannobioside 3 has indeed the same conformational behavior as the natural disaccharide, but exhibits improved stability towards the activity of jack-bean mannosidase.…”