Synthesis and structural study of [2.n](2,5)pyridinophanes

Funaki, Takashi; Inokuma, Seiichi; Ide, Hayato; Yonekura, Tomomi; Nakamura, Yosuke; Nishimura, Jun

doi:10.1016/j.tetlet.2004.01.100

Cited by 7 publications

(12 citation statements)

References 8 publications

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“…In another context, Nishimura and co-workers investigated the synthesis of [2.n](2,5)pyridinophanes 122 possessing a cyclobutane ring and dioxaoligomethylene chains as tethers (Scheme 32). 67 The target compound was efficiently prepared in 84% yield by intramolecular [2+2] photocycloaddition of vinyl pyridine derivative 121. Following this work, the authors also accomplished the synthesis of crownophanes 124 possessing three pyridine rings via the same photocycloaddition from 123, albeit in low efficiency (only 15% yield).…”

Section: Scheme 31 Olefin Cycloaddition In the Total Synthesis Of Rhododaurichromanic Acidsmentioning

confidence: 99%

Recent Synthetic Applications of Catalyst-Free Photochemistry

Liu¹,

Li²

2017

Synlett

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Catalyst-free photochemistry provides numerous opportunities toward sustainable synthesis because catalyst separation can usually be avoided, which is consistent with green chemistry principles. Complementary to the well-reviewed photoredox chemistry, this review specifically summarizes the synthetic applications of photochemistry without external catalysts reported since 2000. The selected examples include both natural product synthesis and new methodology development. This review is arranged based on the type of chromophore. It is our hope that this review will inspire more synthetic chemists to embrace photochemistry into their research plans.1 Introduction2 Photochemistry of Olefins2.1 [2+2] Cycloaddition of Enones and Olefins2.2 Cycloaddition of Olefins without Carbonyl Groups2.3 Z/E Isomerization2.4 Cyclization2.5 Others3 Photochemistry of C=O3.1 The Paternò–Büchi Reaction3.2 The Yang Photoenolization3.3 The Norrish Type I Reaction3.4 The Norrish Type II Reaction3.5 Others4 Photochemistry of Nitrogen-Containing Functional Groups5 Photochemistry of Halogen-Containing Compounds6 Conclusion and Outlook

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Section: Scheme 31 Olefin Cycloaddition In the Total Synthesis Of Rhododaurichromanic Acidsmentioning

confidence: 99%

Recent Synthetic Applications of Catalyst-Free Photochemistry

Liu¹,

Li²

2017

Synlett

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“…X-Ray crystallography gave definite structural evidence for the most-important and major products 2, 6, and 9, as shown in Fig. 1 [6]. Between 2 and 3, and among 9, 10, and 11, no isomerization was observed over several months, as well as for 6 and 7 (not obtained).…”

mentioning

confidence: 89%

“…By irradiation under preparative conditions (see Exper. Part), it gave the cisisomers [6] exo,syn-2 and anti-3 in 84% yield. Note that in isomer 2, the N-atoms of the pyridine rings are exo-oriented relative to the cyclobutane ring.…”

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confidence: 94%

“…± The [2 2] photocycloaddition of the dimeric 3-vinylpyridine derivative 1 gave rise to syn-and anti-pyridinophanes 2 and 3. The major syn-adducts were elucidated as exo-isomers by spectroscopic methods and X-ray crystallography [6]. The unusually high selectivity was thoroughly secured.…”

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confidence: 99%

“…Recently, however, we found another example of a highly stereoselective formation of cyclophane adducts from flexible vinylarene derivatives in nearly quantitative yield [6]. This result prompted us to examine the underlying stereochemical effect.…”

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confidence: 99%

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The exo‐Outstretching Effect Governing the Exclusive Stereoselectivity of the Intramolecular [2+2] Photocycloaddition of Vinylarenes

Nishimura¹,

Funaki²,

Saito³

et al. 2005

Helvetica Chimica Acta

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Dedicated to Professor Rolf Huisgen on the occasion of his 85th birthday Intramolecular [2 2] photocycloaddition of a dimeric vinylpyridine 1 through a singlet-excited species efficiently formed the corresponding syn-and anti-pyridinophanes 2 and 3. The syn-isomers were elucidated spectroscopically and by X-ray crystallography as exo,syn-configured. The high selectivity under formation of exo,syn-2 was thoroughly investigated. Consequently, an exo-outstretching effect, which is observed around the periphery of a face-to-face-oriented system between two aromatic nuclei as a transition state, on cyclobutane ring formation was discovered for the first time.Introduction. ± Rolf Huisgen is one of the pioneers working on reaction mechanisms with the most-sophisticated methods and spectroscopic techniques available in the middle of the last century. His interest has covered reactions proceeding under non-catalytic, catalytic, thermal or photochemical conditions etc. 1 ). His careful and clear formulation of scientific arguments and statements have attracted many scientists through the generations. Moreover, in carrying out kinetics and mechanistic works, his scrutiny in the analysis of results is always understood by his coworkers, by suggesting to them not to ignore any discrepancy, tiny though it may be, which is believed to lead to some new significant discovery. In this paper, we are pleased to present some mechanistic aspects of photochemical reactions arising from a discrepancy observed at the preparative level.Vinylarenes such as styrene have attracted much interest from photochemical and photophysical points of view [2]. Since our discovery of the facile intramolecular [2 2] photocycloaddition of vinylarenes towards cyclophanes in 1986, some stereoselective product formation was often observed on the cyclobutane orientation, although almost all cases show the general selectivity such as exclusive cis-cyclobutane ring formation and selective syn-arrangement of the aromatic rings. In fact, several substrates like 1-vinylnaphthalene derivatives formed an exo-directed cyclobutane ring exclusively, because they have vinyl groups that are entirely exo-directed due to the severe steric interaction between peri-H-atoms and vinyl CH 2 H-atoms [3]. The selectivity can be rationalized by the so-called NEER 2 ) principle [4].

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Syntheses and Properties of Crownophanes

Inokuma

Ito

Nishimura

Topics in Heterocyclic Chemistry

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Synthesis and structural study of [2.n](2,5)pyridinophanes

Cited by 7 publications

References 8 publications

Recent Synthetic Applications of Catalyst-Free Photochemistry

Recent Synthetic Applications of Catalyst-Free Photochemistry

The exo‐Outstretching Effect Governing the Exclusive Stereoselectivity of the Intramolecular [2+2] Photocycloaddition of Vinylarenes

Syntheses and Properties of Crownophanes

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