A novel twist on an old theme: β-Halovinylsilanes, a new elimination approach to oligoyne assembly

This article summarises our recent efforts towards using β-halovinylsilanes in a new approach to oligoyne assembly. β-Halovinylsilanes are particularly useful masked alkynes since the free alkyne can be released under mild reaction conditions by treatment with fluoride. To this end, β-chlorovinylsilane and β-fluorovinylsilane motifs have been incorporated into a 1-trimethylsilyl-hexa-3-en-1,5-diyne scaffold. Oxidative dimerisation of this masked triyne provides a centrosymmetric masked hexayne, which serves as our building block for oligoyne assembly. We have assembled a masked dodecayne using this methodology and shown that treatment of the masked dodecayne with fluoride effects a four-fold dechlorosilylation to provide the corresponding dodecayne, which is the longest aryl end-capped oligoyne reported to date. This long-chain oligoyne proved to be highly unstable. Molecular encapsulation provides a potential solution to the problem of instability associated with long-chain oligoynes, and preliminary results where one of our masked hexaynes was modified in order to form an insulated system are presented.