β-Chlorovinylsilanes as masked alkynes in oligoyne assembly: synthesis of the first aryl-end-capped dodecayne

Simpkins, Simon M.E.; Weller, Michael D.; Cox, Liam R.

doi:10.1039/b707681a

Cited by 36 publications

(35 citation statements)

References 38 publications

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“…One approach is based on the use of masked oligoynes, in which the polyyne framework is assembled in a protected form. 38 In the final step, the linear carbon chain is constructed via elimination of masking functional groups. Recently, the Fritsch–Buttenberg–Wiechell (FBW) rearrangement of carbene/carbenoid intermediates has evolved into a valuable synthetic methodology for the preparation of polyynes from geminal dihaloolefin-masked acetylene precursors.…”

Section: Resultsmentioning

confidence: 99%

Polyyne Rotaxanes: Stabilization by Encapsulation

et al. 2016

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Active metal template Glaser coupling has been used to synthesize a series of rotaxanes consisting of a polyyne, with up to 24 contiguous sp-hybridized carbon atoms, threaded through a variety of macrocycles. Cadiot–Chodkiewicz cross-coupling affords higher yields of rotaxanes than homocoupling. This methodology has been used to prepare [3]rotaxanes with two polyyne chains locked through the same macrocycle. The crystal structure of one of these [3]rotaxanes shows that there is extremely close contact between the central carbon atoms of the threaded hexayne chains (C···C distance 3.29 Å vs 3.4 Å for the sum of van der Waals radii) and that the bond-length-alternation is perturbed in the vicinity of this contact. However, despite the close interaction between the hexayne chains, the [3]rotaxane is remarkably stable under ambient conditions, probably because the two polyynes adopt a crossed geometry. In the solid state, the angle between the two polyyne chains is 74°, and this crossed geometry appears to be dictated by the bulk of the “supertrityl” end groups. Several rotaxanes have been synthesized to explore gem-dibromoethene moieties as “masked” polyynes. However, the reductive Fritsch–Buttenberg–Wiechell rearrangement to form the desired polyyne rotaxanes has not yet been achieved. X-ray crystallographic analysis on six [2]rotaxanes and two [3]rotaxanes provides insight into the noncovalent interactions in these systems. Differential scanning calorimetry (DSC) reveals that the longer polyyne rotaxanes (C16, C18, and C24) decompose at higher temperatures than the corresponding unthreaded polyyne axles. The stability enhancement increases as the polyyne becomes longer, reaching 60 °C in the C24 rotaxane.

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Section: Resultsmentioning

confidence: 99%

Polyyne Rotaxanes: Stabilization by Encapsulation

et al. 2016

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“…The synthesis of polyynes beyond 20 carbons in length has been nothing less then a monumental synthetic challenge, one for which there still remains Cox and coworkers recently reported the synthesis of the first aryl endcapped dodecayne using a very interesting new strategy of b-chlorovinylsilane elimination (Scheme 23) [112]. In this case, the masked precursor, which contains all 24 carbons of the dodecayne skeleton, has been assembled through a series of oxidative homocoupling events using modified EglintoneGlasereHay coupling conditions (Cu(OTf) 2 , TMEDA, CH 2 Cl 2 , O 2 ).…”

Section: Decaynes and Beyondmentioning

confidence: 99%

Synthesis of extended polyynes: Toward carbyne

Chalifoux

Tykwinski

2008

Comptes Rendus. Chimie

125

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“…To this end, we recently dimerised masked hexayne 31a to afford the corresponding masked dodecayne 34 (Scheme 12). Exposure of 34 to TBAF provided the corresponding dodecayne 35, which represents the longest aryl end-capped oligoyne reported to date [39]. Dodecayne 35 proved to be highly unstable, even under the very dilute reaction concentrations which were used to effect unmasking; however, this oligoyne was characterised by UVevis spectroscopy and MALDI-TOF mass spectrometry.…”

Section: Application To the Synthesis Of An Aryl End-capped Dodecaynementioning

confidence: 99%