Generation and oligomerization of bicyclo[2.2.2]octyne and properties of tris(bicyclo[2.2.2]octeno)benzene obtained from the linear trimer

Komatsu, Kôichi; Aonuma, Shuji; Jinbu, Yasuhisa; Tsuji, Ryotaro; Hirosawa, Chitaru; Takeuchi, Ken′ichi

doi:10.1021/jo00001a039

Cited by 68 publications

(34 citation statements)

References 2 publications

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“…One of Koichi Komatsu's (Nozoe lecturer at ISNA-11 in St. John's) entries (Figure 7) was also synthesized by a cyclotrimerization of a strained alkyne ([2.2.2]bicyclooctyne). [54] This compound not only played an important role in Komatsu's studies of radical cations of aromatic compounds, but bears close structural resemblance to a compound later reported by Sakurai and Hirao. Compound 61 (the minor component of a 1:3 mixture with it's anti isomer) was synthesized from precursor 60 by a copper-mediated formal cyclotrimerization that does not involve a strained .…”

Section: Cyclotrimerizationmentioning

confidence: 69%

Extraordinary Transformations to Achieve the Synthesis of Remarkable Aromatic Compounds

Bodwell

2014

The Chemical Record

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Note from the Editor: When we walk around a sculpture, it can speak to us in many ways, sometimes quite differently from various view points. Central to Tetsuo Nozoe and the Nozoe Autograph Book project are novel aromatic compounds. Just look at nearly any page and such compounds jump out at us. We can categorize them in many ways. Their structures. Their physical properties. Their pharmacological and toxicological properties. Their commercial utilities. Their symmetry. Their size. In this essay, Graham Bodwell brings to us his analysis of the various ways in which some of the most remarkable of these compounds have been ingeniously synthesized. We are privileged to have Bodwell's vision and his sense of organization and beauty. Tetsuo Nozoe would have beamed! —Jeffrey I. Seeman Guest Editor University of Richmond Richmond, Virginia 23173, USA E‐mail: jseeman@richmond.edu

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Section: Cyclotrimerizationmentioning

confidence: 69%

Extraordinary Transformations to Achieve the Synthesis of Remarkable Aromatic Compounds

Bodwell

2014

The Chemical Record

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“…5 In a first attempt to improve the yields of the cyclotrimerization of 2,3-dibromobicyclo[2.2.2]oct-2-ene, K. Komatsu introduced nickel(0) to stabilize the alkyne intermediate, although finally the role of the metal resulted negligible. 6 An important progress in the synthesis of BCTs has been the use of copper(I), which causes a copperÀlithium exchange, leading to improved chemo-selectivity, presumably avoiding the alkyne intermediate. This procedure, that has been developed in 1996 in our group, allowed to prepare for the first time benzotrinorbornene and benzotribenzobornane in yields up to 50%.…”

Section: Benzocyclotrimers: Synthesismentioning

confidence: 99%

Benzocyclotrimers: From the Mills−Nixon Effect to Gas Hosting

et al. 2011

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The formal annulation of three bicylic olefins yields a class of molecules termed benzocyclotrimers (BCTs), which have unusual electronic properties. The bonds in the central aromatic ring, for example, alternate in length: rather than resembling a substituted benzene, a BCT instead evokes comparison to a cyclohexatriene. Forty years have passed since the synthesis of heptiptycene, the first BCT, was reported. In the interim, many methods have been developed for preparing tris-bicycloannulated benzenes. More than thirty different BCTs have so far been reported, with a variety of morphological features and properties. Over the same period, yields have increased from just a few percent to almost quantitative conversion. This improvement in synthetic access has expanded interest beyond the original theoretical considerations (bond-length fixation in aromatics) to functional applications (supramolecular scaffolds). In this Account, we describe the evolution of synthetic approaches to BCTs and their derivatives, as well as the applications that are now being explored for these compounds. Early syntheses of BCTs involved chloroolefins treated with butyl lithium. A strained alkyne intermediate was postulated early on, and was indeed trapped in 1981. Subsequent efforts have focused on improving chemoselectivity by mitigating the drastic conditions required for the generation of the alkyne intermediate. Our introduction of Cu(I) to induce lithium-copper exchange was successful in this regard. Further improvement resulted from the use of bicylic bromo(trimethylstannyl)olefins. In an effort to avoid the toxicity of the tin reagents, the Heck reaction and Pd catalysis have been pursued for cyclotrimerizing bicylic bromo- and iodoolefins. Depending on the symmetry of the starting bicylic olefin, two diastereomers can be obtained in the preparation of a BCT: a syn compound with C(3) symmetry and an anti compound with C(s) symmetry. Studying the diastereomeric outcome in a variety of synthetic approaches has yielded valuable insight into the cyclotrimerization reaction. Moreover, highly symmetric compounds, such as a D(3)-symmetric trindane and C(3v)-symmetric sumanene, have been prepared as BCT derivatives. The structure of BCTs offers a versatile three-dimensional scaffold for studying molecular recognition. Like calixarenes, BCTs form complexes with a variety of guest molecules. Recent developments include the trapping of gases in a hydrogen-bonded dimer and the encapsulation of larger molecules within a covalently linked condensation derivative. Future innovations in this fertile research area will likely include highly functionalized curved aromatics, receptors, and sensors.

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“…When 21 was reacted with an equivalent amount of BuLi in THF at low temperature, a series of oligomers Br‐(BCO) n ‐Br ( 22 , n = 2–5) were obtained in a total yield of around 60%. This reaction is believed to proceed through the formation of highly strained acetylene 23 as an intermediate, as shown in Scheme ; in fact, a trapping experiment proved the efficient formation of 23 . The oligomers 22 can be easily separated by the use of gel permeation chromatography.…”

Section: Stabilization Of the Tropylium Ion By σ–π Conjugationmentioning

confidence: 95%

Professor Tetsuo Nozoe and My Tropylium Ion Chemistry

Komatsu

2014

The Chemical Record

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Needless to say, the discovery of hinokitiol with its "unconventional" aromaticity by Professor Tetsuo Nozoe is one of the most important achievements in organic chemistry in the last century. The essence of this "non-benzenoid" aromaticity in hinokitiol is of course that of tropolone, and it is further related to the aromaticity of tropone and the tropylium ion, i.e., the cycloheptatrienyl cation. In this account, details of the study conducted by the author's group, particularly on the synthesis and properties of tropylium ion derivatives with various unique structures pursuing the ultimately high carbocation stability, are described.

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Generation and oligomerization of bicyclo[2.2.2]octyne and properties of tris(bicyclo[2.2.2]octeno)benzene obtained from the linear trimer

Cited by 68 publications

References 2 publications

Extraordinary Transformations to Achieve the Synthesis of Remarkable Aromatic Compounds

Extraordinary Transformations to Achieve the Synthesis of Remarkable Aromatic Compounds

Benzocyclotrimers: From the Mills−Nixon Effect to Gas Hosting

Professor Tetsuo Nozoe and My Tropylium Ion Chemistry

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