64312-89-6Relevant articles and documents
A Stimuli-Responsive Macromolecular Gear: Interlocking Dynamic Helical Polymers with Foldamers
Freire, Félix,Qui?oá, Emilio,Riguera, Ricardo,Rodríguez, Rafael,Suárez-Picado, Esteban
supporting information, p. 8616 - 8622 (2020/04/15)
Herein, macromolecular gears composed of helical poly(phenylacetylenes) (PPAs) bearing short oligopeptides as pendant groups are described, in which the two structural motifs (framework and substituents) are combined. These gears are obtained by polymerization of the acetylene groups introduced at the C-terminus of short oligopeptides formed by achiral (Aib)n units (n=1–3) derivatized at the N-terminus by a single enantiomer (R or S) of α-methoxy-α-trifluoromethylphenylacetic acid (MTPA, Mosher's reagent). The chiral information of the MTPA is transmitted to the achiral Aib fragments and, through either chiral tele-induction and/or chiral harvesting mechanisms, is further transferred to the polyene backbones, which adopt preferentially P or M helical senses. Moreover, these materials also show dynamic behavior and respond to the action of external stimuli by either inverting the P/M sense and/or modifying the elongation in fully reversible processes.
Hydrogen-bond-assisted helical folding of propeller-shaped molecules: Effects of extended π-conjugation on chiral selection, conformational stability, and exciton coupling
Opsitnick, Elizabeth A.,Jiang, Xuan,Hollenbeck, Andrew N.,Lee, Dongwhan
supporting information; experimental part, p. 708 - 720 (2012/03/22)
Cooperative interaction between multiple chiral centers dictates the absolute handedness of structural folding. We have designed and prepared a series of chiral C3-symmetric tris(N-salicylidenamine) derivatives that adopt three-blade propeller-like conformations. Synthetic access to an expanded family of such constructs was aided by enzymatic resolution and C-C cross-coupling reactions of aryl-substituted chiral propargylic alcohol derivatives. These key structural components were integrated into molecular propellers of predetermined helical screw sense. Through comparative studies on a homologous set of molecules, we found that installation of phenylene-ethynylene-derived π-conjugation profoundly affected the stabilities of the helically folded structures, as evidenced by UV/Vis and circular dichroism (CD) studies. Increasing the number of hydrogen bonds through additional substitution also enhanced the populations of the folded conformations in solution. In addition to introducing steric bias to control structural folding, linearly π-conjugated groups function as spatially well-defined chromophores that give rise to characteristic exciton-coupled circular dichroism. Absolute configurations of chiral centers could thus be further confirmed by comparing the torsional relationships between pairs of chromophores on adjacent subunits, which are fully consistent with the computationally predicted structural models. Twist to fold: Chiral alcohol groups effectively direct the absolute helicities of three-bladed propeller-shaped C3-symmetric molecules through tight O-H...O-H contacts. The stabilities of the conformations of these systems depend upon the numbers of hydrogen bonds and the steric bulk of the π-conjugated substituents on thestereogenic centers. Copyright
1-Benzotriazol-1-yl-3,3,3-trifluoro-2-methoxy-2-phenylpropan-1-ones: Mosher-Bt reagents
Katritzky, Alan R.,Mohapatra, Prabhu P.,Fedoseyenko, Dmytro,Duncton, Matthew,Steel, Peter J.
, p. 4268 - 4271 (2008/02/05)
(Chemical Equation Presented) Benzotriazole derivatives of 3,3,3-trifluoro-2-methoxy-2-phenylpropionic acid react with water-soluble amino acids and peptides in an acetonitrile/water (2:1) mixture to give the corresponding amides in quantitative yield.
