Cycloaddition reactions of cyclophanes

Misumi, Soichi

doi:10.1351/pac198759121627

Cited by 20 publications

(5 citation statements)

References 8 publications

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“…In paracyclophanes (Figure left, molecule 1 ), well-known molecules where benzene rings are forced to be near each other, the separation between two ring carbons is as low as 2.6 Å. (1,3,5)Cyclophanes ( 2 ), superphane ( 3 ), and Si-bridged paracyclophanes ( 4 ) are known, as are multilayered cyclophanes . These are models for the bonding arrangement in the R 3̅ m structure.…”

Section: Resultsmentioning

confidence: 99%

The Unusual and the Expected in the Si/C Phase Diagram

2013

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In the Si/C phase diagram, the only stable phases at P = 1 atm are the numerous polytypes of the simplest 1:1 stoichiometry, SiC. However, many metastable yet likely to be kinetically persistent phases can be found for almost any composition. Given the instability of simple graphite-type structures with considerable Si content, we thought these metastables would be only of the diamondoid class. Indeed they are for Si3C, a stoichiometry we studied on the silicon-rich side of the phase diagram. Yet on the carbon-rich side, which we chose to explore computationally with SiC3, there was a surprise in store, a series of unusual metastable structures. The most striking of these had the appearance of a collapsed graphite structure, with benzenoid C6 units and SiSi bridges between layers. This SiC3 structure is related to known meta-(1,3,5)cyclophanes. Three other metastable structures featured layers with all carbon polyene and polyphenylene arrays. Some of these can be metallic, as we have found.

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Section: Resultsmentioning

confidence: 99%

The Unusual and the Expected in the Si/C Phase Diagram

2013

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“…With gram quantities of pyrenophanes 2b and 2c in hand, a study of their chemistry was undertaken. In view of the propensity for strained cyclophanes to undergo cycloaddition reactions, the behavior of 2b and 2c toward reactive dienophiles was investigated first. As we reported earlier, the reaction of 2b with tetracyanoethene (TCNE) afforded 1:1 adduct 4b (Scheme ) 5a…”

Section: Resultsmentioning

confidence: 99%

Nonplanar Aromatic Compounds. 3. A Proposed New Strategy for the Synthesis of Buckybowls. Synthesis, Structure and Reactions of [7]-, [8]- and [9](2,7)Pyrenophanes

et al. 2000

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A new strategy for the synthesis of Buckybowls is presented and initial attempts to implement it are reported. This involves annulation of further rings onto polycyclic aromatic systems that prefer to be planar but have been "pre-bent" by the installation of a tether. Pyrenophane 2b reacts with TCNE and PTAD to give 1:1 and 1:2 adducts, respectively. The less strained pyrenophane 2c is unreactive toward TCNE but gives a 1:2 adduct with PTAD. Attempted electrophilic aromatic brominations of pyrenophane 2e under a variety of conditions were unsuccessful, as were attempts to brominate cyclophanediene 1c, the direct synthetic precursor of 2c. Tether cleavage and addition reactions occurred rather than substitution. In an effort to circumvent tether cleavage problems, [7]-, [8]- and [9](2,7)pyrenophanes 22b-d were prepared. However, attempted bromination and Friedel-Crafts acylations failed. Evidence for the fleeting existence of [6](2,7)pyrenophane 22a was also obtained. Comparison of structural data (X-ray and AM1 calculations) for the pyrenophanes 22a-d with their 1,n-dioxa analogues 2a-d indicates that the nature of the tether has a strong effect on the degree of bend in the pyrene moiety and this led to the identification of trioxapyrenophane 28 as the next target in the quest for increasingly bent pyrenes.

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“…1 For their unique structures, cyclophanes have much attracted interests in polymer science, 2 organometallic chemistry, 3 biology, 4 and molecular recognition chemistry 5 for application, such as chiral catalysts 6 and optoelectronic materials. 7 Many cyclophane-based compounds containing various aromatic moieties, such as naphthalene (naphthalenophane), 8 anthracene (anthracenophane), 9 or pyrene (pyrenophane), 10 have been reported for the investigation of the unique molecular recognition behavior and the optical or electronic property. On the other hand, cyclophane compounds bridged by siloxane bondings have been reported to attract much attention because of their unique optical and electronic properties based on the s*ep* conjugation between silylene moiety and aromatic one.…”

Section: Introductionmentioning

confidence: 99%