Unusual Formation of a Cyclyne Dimer and an Indenoindene Derivative

Chakraborty, Meenakshi; Tessier, Claire A.; Youngs, Wiley J.

doi:10.1021/jo982111a

Cited by 53 publications

(31 citation statements)

References 30 publications

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“…The treatment of 2-bromo-4-methyl-1-(2-trimethylsilylethynyl)benzene (4) with a Ni 0 complex, generated from the reduction of [NiCl 2 A C H T U N G T R E N N U N G (PPh 3 ) 2 ] with zinc dust in THF in the presence of Et 4 NI, [6c] furnished the corresponding biaryl 5 in 30 % yield. Surprisingly, the reaction was carried out in the absence of Et 4 NI to produce 6 in approximately 20 % with high reproducibility (Scheme 2).…”

Section: Resultsmentioning

confidence: 99%

“…[4] This reaction, however, seems to be an exceptional case because the reaction of 2-iodo-1-ethynylbenzenes Abstract: An extremely simple dibenzopentalene synthesis from readily available 2-bromo-1-ethynylbenzenes using a nickel(0) complex is described. Although the yields are moderate, the formation of three C À C bonds in a single process and the high availability of the starting materials are important advantages of this reaction.…”

Section: Introductionmentioning

confidence: 99%

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An Extremely Simple Dibenzopentalene Synthesis from 2‐Bromo‐1‐ethynylbenzenes Using Nickel(0) Complexes: Construction of Its Derivatives with Various Functionalities

Kawase

Konishi

Hirao

et al. 2009

Chemistry A European J

118

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Nice and easy: A very simple synthesis for dibenzopentalenes, which starts from 1-bromo-2-ethynylbenzenes, has been developed. It uses Ni(0) complexes (see scheme), from which a relatively stable Ni(II) complex as an important intermediate has been isolated. Dibenzopentalenes with various functional groups can be prepared by the procedure, and their electronic properties are consistent with theoretical calculations.An extremely simple dibenzopentalene synthesis from readily available 2-bromo-1-ethynylbenzenes using a nickel(0) complex is described. Although the yields are moderate, the formation of three C-C bonds in a single process and the high availability of the starting materials are important advantages of this reaction. The corresponding aryl-nickel(II) complex as an important intermediate was isolated as relatively stable crystals, and the structure was confirmed by X-ray crystallographic analysis. The high stability of this complex should play a key role in this reaction. The reaction is applicable to the preparation of dibenzopentalenes bearing various functional groups. Their electronic properties are consistent with theoretical calculations. The cyclic voltammograms of these compounds reveal highly amphoteric redox properties. In particular, the electron-donating property of a tetramethoxy derivative is greater than that of oligothiophenes and dibenzodithiophenes and almost comparable to that of pentacene.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An Extremely Simple Dibenzopentalene Synthesis from 2‐Bromo‐1‐ethynylbenzenes Using Nickel(0) Complexes: Construction of Its Derivatives with Various Functionalities

Kawase

Konishi

Hirao

et al. 2009

Chemistry A European J

118

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“…This indicates that strained eight-membered DBA 14c was a major initial product of the cyclization reaction (Scheme 1). [27] Scheme 1.…”

Section: Strained Dehydrobenzo[8]annulenes ([8]dbas)mentioning

confidence: 99%

Strained Dehydrobenzoannulenes

2006

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Dehydrobenzoannulenes (DBAs) have been attracting a great deal of interest as a result of their potential applications as optoelectronic materials, precursors of new forms of carbon materials, and as building blocks for hitherto‐unknown 2D carbon networks consisting of sp and sp2 carbon atoms. Among the DBAs, those with substantial strain due to bond‐angle deformation at the triple bonds exhibit greater potential as electronic communication units and precursors of new polycyclic, conjugated ring systems owing to their high reactivity towards carbon–carbon bond‐forming reactions. It is also of interest to see how the deformation of triple bonds affects the cyclic conjugation of π systems, that is, the aromaticity/antiaromaticity of DBAs. This article reviews these characteristic aspects of strained DBAs. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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“…[8] More recently, Youngs et al invoked Sonogashira coupling to dimerize an ortho-ethynyl iodobenzene derivative with bulky substituents at ortho-positions, yet only a 10 % yield of the desired cyclophane was obtained. [9] The low yield was ascribed to the highly reactive acetylenic bonds of the product under the reaction conditions. It is apparent, therefore, that the direct CÀC bond formation at terminal acetylenes is not easy to generate cyclic acetylenes on account of the propensity of the sp carbon to adopt the linear disposition.…”

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confidence: 99%