9‐Borafluorene

Köster, Roland; Benedikt, G.

doi:10.1002/ange.19630750909

Cited by 40 publications

(28 citation statements)

References 5 publications

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“…In the early 1960's Eisch and Kaska reported on the first group 13 heterofluorene, 9‐phenyl‐9‐aluminafluorene, by elimination of benzene from (2‐biphenyl)‐(diphenyl)aluminium . Analogously, Köster and Benedikt obtained 9‐alkyl‐, 9‐aryl‐ and 9‐chloro‐borafluorenes . Nöth and Narula synthesized 9‐halo‐9‐borafluorenes using 2,2′‐biphenylen‐mercury and boron halides .…”

Section: Introductionmentioning

confidence: 99%

Synthesis of 9‐Gallafluorenes via Group 12 Metal Biphenylenes

2018

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9-Gallafluorenes were synthesized from 9-zincafluor-ene·tmeda as an alternative to 2,2′-biphenylenmercury and 2,2′-dilithiobiphenyl. The zincafluorene was found to be only one possible form of a biphenylene zinc. In dependence of the synthetic conditions a dimeric zinc bridged structure resulted, too. The gallafluorenes obtained were stabilized by nitrogen donors or formed dimers in case of 9-tert-butoxygallafluorene. That means, all of these derivatives contained tetra coordinated

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Section: Introductionmentioning

confidence: 99%

Synthesis of 9‐Gallafluorenes via Group 12 Metal Biphenylenes

2018

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“…However, the diversity in substitution patterns at the butadiene backbone is less developed. Apart from benzannelated boroles (9‐borafluorenes and boraindenes), which are known to reveal different electronic properties, only a few derivatives of stable free boroles with a backbone other than a tetraphenylbutadiene are documented in the literature (Scheme ). Yamaguchi reported on electron‐rich thienyl groups in the butadiene backbone, which led to markedly altered HOMO–LUMO gaps .…”

Section: Introductionmentioning

confidence: 99%

Electronic Push–Pull Modulation by Peripheral Substituents in Pentaaryl Boroles

Heitkemper

Sindlinger

2019

Chemistry A European J

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Establishing access to a bulky tetraaryl dilithiobutadiene (Ph*C)4Li2 (Ph*=3,5‐tBu2(C6H3)) allowed for the synthesis of five‐membered heterocycles with incorporated main‐group elements. Along with an amino borole, a set of substituted pentaaryl boroles (Ph*C)4BAr has been synthesized. The examination of their absorption spectra and computational studies by means of DFT granted insight into the influence of peripheral substituents on the electronic features of the parent pentaphenyl borole (PhC)4BPh. Introduction of the more electron‐rich Ph* residue at the carbon atoms increases the HOMO energy, redshifting the visible π/π*‐absorption bands compared with the parent pentaphenyl borole. The influence on the frontier orbitals of three different boron‐bound aryls with electronically modulating substituents in the remote 3,5‐positions Ar=3,5‐R2‐C6H3 (R=Me, H, CF3) was studied. The substituents were found to increase (+I effect, Me) or decrease (−I effect, CF3) the LUMO energy, thus directly affecting the visible absorption spectra. This represents the first study on HOMO–LUMO‐gap adjustments by a combined push–pull approach of a substituted pentaphenylborole.

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“…They were first synthesized by Köster and Benedikt in 1963 11,12 and by Narula and Nöth in 1985, 13 but the most efficient synthesis was developed only recently by Holthausen, Wagner and coworkers (Scheme 2). 14,15,16 2,2'-Dibromobiphenyl 1 underwent double lithium-bromine exchange, followed by lithium-boron exchange 15 delivering desired 9-chloro-9-borafluorene 2.…”

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confidence: 99%

Radical chain reactions involving 9-alkyl-9-borafluorenes

Gorokhovik¹,

Rieder²,

Povie³

et al. 2014

Arkivoc

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The preparation of 9-alkyl-9-borafluorenes and their use as radical precursors in chain reactions were investigated. These organoboranes were found to be excellent precursors of primary and secondary alkyl radicals. Reactions were readily initiated by traces of oxygen and efficient processes involving sulfonyl-based radical traps were discovered. Due to the very high reactivity of the intermediate 9-H and 9-alkyl-9-borafluorenes, problems of reproducibility were identified.

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9‐Borafluorene

Cited by 40 publications

References 5 publications

Synthesis of 9‐Gallafluorenes via Group 12 Metal Biphenylenes

Synthesis of 9‐Gallafluorenes via Group 12 Metal Biphenylenes

Electronic Push–Pull Modulation by Peripheral Substituents in Pentaaryl Boroles

Radical chain reactions involving 9-alkyl-9-borafluorenes

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