Long-distance chirality transfer in polymerization of isocyanides bearing a remote chiral group

Chen, Jianping; Gao, Jianmei; Wang, Zhi Yuan

doi:10.1002/(sici)1097-0126(199709)44:1<83::aid-pi820>3.0.co;2-t

Cited by 23 publications

(7 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…7) described by Chen et al also affords materials that show appreciable optical activity with opposite sign at the D line to that of the monomers. 40 The optical rotation of the polymer prepared from 17 did not present very high optical activity, an observation which inferred smaller diastereoselectivity in the reaction as a result of the greater flexibility of the monomer when compared with 18. The CD spectra of the polymers showed Cotton effects at the position normally assigned to the polymer backbone at 363 nm, as well as others at higher wavelengths.…”

Section: Spacer Effects In Chiral Inductionmentioning

confidence: 99%

Long‐range effects of chirality in aromatic poly(isocyanide)s

Amabilino

Serrano

Sierra

et al. 2006

J. Polym. Sci. A Polym. Chem.

View full text Add to dashboard Cite

The preparation of optically active atropoisomeric polymers which present chiral backbones, thanks to induction during their synthesis from stereogenic centers, located far away from the skeleton is possible, thanks principally to semirigid conformations of the promesogenic spacers between them. The result is that chiral “information” can be passed as far as 21 Å from the asymmetric center to the carbon atom that forms the polymeric chain in poly(isocyanide)s. The sense of chiral induction in these conformationally rigid polymers parallels the helical sense of the cholesteric phases, as well as to the helical senses of chiral smectic C phases, induced by the monomers in nematic and smectic C phases, respectively. All these phenomena obey the odd–even rules proposed for chiral sense changes in these liquid crystalline phases. Noncovalent interactions play an important part in the induction process, in which steric arguments can be used to justify the inductions observed. The methodology can be used to prepare macromolecules, which display switching behavior upon thermal or electrochemical stimulus. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3161–3174, 2006

show abstract

Section: Spacer Effects In Chiral Inductionmentioning

confidence: 99%

Long‐range effects of chirality in aromatic poly(isocyanide)s

Amabilino

Serrano

Sierra

et al. 2006

J. Polym. Sci. A Polym. Chem.

View full text Add to dashboard Cite

show abstract

“…During the last decades, helicenes—ortho-fused polycyclic aromatic hydrocarbons (PAHs), in which benzene building blocks are annulated at an angle of 60° to form helically-shaped molecules 1 —have received considerable attention from the organic 2 , and physical chemistry 3 , and material science communities 4,5 due to their unique features in optics (chiroptical activity 6 , nonlinear optics 3 , and circular polarization 7 ) and chiral sensing (chemical sensors) 8,9 along with exceptional properties in organocatalysis 4,10,11 and distinctive molecular structures (Fig. 1) 12 .…”

Section: Introductionmentioning

confidence: 99%

Gas phase synthesis of [4]-helicene

Zhao

Kaiser

et al. 2019

Nat Commun

View full text Add to dashboard Cite

A synthetic route to racemic helicenes via a vinylacetylene mediated gas phase chemistry involving elementary reactions with aryl radicals is presented. In contrast to traditional synthetic routes involving solution chemistry and ionic reaction intermediates, the gas phase synthesis involves a targeted ring annulation involving free radical intermediates. Exploiting the simplest helicene as a benchmark, we show that the gas phase reaction of the 4-phenanthrenyl radical ([C 14 H 9 ] • ) with vinylacetylene (C 4 H 4 ) yields [4]-helicene (C 18 H 12 ) along with atomic hydrogen via a low-barrier mechanism through a resonance-stabilized free radical intermediate (C 18 H 13 ). This pathway may represent a versatile mechanism to build up even more complex polycyclic aromatic hydrocarbons such as [5]- and [6]-helicene via stepwise ring annulation through bimolecular gas phase reactions in circumstellar envelopes of carbon-rich stars, whereas secondary reactions involving hydrogen atom assisted isomerization of thermodynamically less stable isomers of [4]-helicene might be important in combustion flames as well.

show abstract

“…The opposite sign of R-(-)-P0 to its monomer and a large increase in chiral optical power indicate that the optical activity of R-(-)-P0 is not solely attributed to the configurational chirality in the side groups and suggest that a higher chiral structure, most likely secondary helical structure, has been formed. [33][34][35][36] Changing the configuration of the stereocenters in the chiral tails from R to S as in S-(+)-M0 leads to an inversion of the sign of optical rotation for both monomer and polymer, suggesting the remarkable role of the stereocenter in induction of helical sense. All the other three monomers, S-(+)-M1 to S-(+)-M3, have positive optical rotations like S-(+)-M0 since they have similar chemical structures and identical stereogenic centers.…”

mentioning

confidence: 99%