Synthesis of planar-chiral bridged bipyridines and terpyridines by metal-mediated coupling reactions of pyridinophanes

Kanomata, Nobuhiro; Suzuki, Jun; Kubota, Hisao; Kiichiro, Nishimura; Enomoto, Terumichi

doi:10.1016/j.tetlet.2009.03.095

Cited by 10 publications

(6 citation statements)

References 34 publications

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“…Pyridinophanes, being capable of metal coordination and hydrogen bonding, have been widely utilized as a scaffold for advanced materials . Consequently, a considerable amount of effort has been devoted to the synthesis of racemic and enantiomeric pyridinophanes.…”

Section: Results and Discussionmentioning

confidence: 99%

“…Pyridinophanes, being capable of metal coordination and hydrogen bonding, have been widely utilized as a scaffold for advanced materials. 28 Consequently, a considerable amount of effort has been devoted to the synthesis of racemic and enantiomeric pyridinophanes. In the present study, [2.2]pyridonophane 1 was prepared by photochemical desulfurization of dithia[3.3]pyridinophane 2, according to the literature procedures.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Protonation-Induced Sign Inversion of the Cotton Effects of Pyridinophanes. A Combined Experimental and Theoretical Study

2017

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The circular dichroisms (CDs) of planar chiral [2.2]- and [3.3]-pyridinophanes were investigated experimentally and theoretically. Strong multisignate Cotton effects, typical for cyclophane derivatives, were observed. The CD spectra of [2.2]- and [3.3]-paracyclophanes closely resembled in pattern each other, despite the much greater conformational variations in the latter. Upon protonation, both of the cyclophanes suffered dramatic CD spectral changes with accompanying complete sign inversion, which was attributed to the reversal of diploe moment of pyridinium versus pyridine moiety. This chiroptical property switching driven by protonation/deprotonation was temperature-dependent and hence applicable to thermal sensing. The protonated forms of pyridinophanes served as ideal model systems for studying the cation-π interactions and their effects on chiroptical properties. Thus, the molar CD (Δε) of the charge-transfer band of protonated [2.2]pyridinophane was 10-fold larger than that of protonated [3.3]pyridinophane, which exceeds the increased interplane electronic interactions assessed from the electronic coupling element values.

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Section: Results and Discussionmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Protonation-Induced Sign Inversion of the Cotton Effects of Pyridinophanes. A Combined Experimental and Theoretical Study

2017

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“…Pyridinophanes have been widely exploited as scaffolds for advanced materials utilizing the pyridine unit as a metal coordination or hydrogen-bonding site for constructing supramolecular assemblies and architectures. − Possessing the inherent planar chirality, heterocyclophanes and substituted cyclophanes have been the subject of intensive experimental and theoretical studies and also employed as key components in various applications. − …”

Section: Introductionmentioning

confidence: 99%

A Combined Experimental and Theoretical Study on the Circular Dichroism of Staggered and Eclipsed Forms of Dimethoxy[2.2]-, [3.2]-, and [3.3]Pyridinophanes and Their Protonated Forms

2017

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The circular dichroisms (CDs) of dimethoxy[2.2]-, [3.2]-, and [3.3]pyridinophanes and their protonated forms were investigated experimentally and theoretically. Characteristic multisignate Cotton effects (CEs), typical for planar chiral cyclophane derivatives, were observed. The CD spectral pattern was quite comparable for the staggered forms of [2.2]-, [3.2]-, and [3.3]cyclophanes, but significantly differed for the eclipsed forms. More interestingly, the patterns resembled, but the CE signs were practically opposite between staggered and eclipsed [2.2]pyridinophanes. Upon protonation, the signs of most CEs were inverted in both forms of cyclophanes, due to the reversal of dipole moment in the pyridine against the pyridinium moiety. Such a change in CD spectrum upon protonation was not apparent in [3.2]pyridinophane, and the CD spectral behavior was more complex in [3.3]pyridinophanes. The variation of CD caused by the protonation/deprotonation process was temperature-dependent and hence utilized as a thermal sensor. The protonated forms of the homologous pyridinophanes with different tether lengths in staggered and eclipsed forms served as a model system for systematically studying the cation-π interaction and its effects on chiroptical properties. A steady increase of electronic interaction became apparent for the smaller-sized cyclophanes from the increased excitation energy and electronic coupling element of the charge-transfer (CT) band, while the observed CE at the CT band was a more complex function of the original transition dipole of donor/acceptor pair and linker atoms, as well as the strength of the electronic interaction.

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“…Chiral cyclophane-based heteroaromatics is a field ripe for exploration. [4][5][6][7][8] We are interested in the synthesis of planar chiral [2.2]paracyclophane derivatives 9 and in this communication, we disclose a rapid route to planar chiral pyridine N-oxides and reveal their potential as Lewis base catalysts.…”

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confidence: 99%

Facile synthesis of planar chiral N-oxides and their use in Lewis base catalysis

et al. 2011

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Synthesis of planar-chiral bridged bipyridines and terpyridines by metal-mediated coupling reactions of pyridinophanes

Cited by 10 publications

References 34 publications

Protonation-Induced Sign Inversion of the Cotton Effects of Pyridinophanes. A Combined Experimental and Theoretical Study

Protonation-Induced Sign Inversion of the Cotton Effects of Pyridinophanes. A Combined Experimental and Theoretical Study

A Combined Experimental and Theoretical Study on the Circular Dichroism of Staggered and Eclipsed Forms of Dimethoxy[2.2]-, [3.2]-, and [3.3]Pyridinophanes and Their Protonated Forms

Facile synthesis of planar chiral N-oxides and their use in Lewis base catalysis

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