Thio-bromo chemistry

In this final example of the broad applicability the thiol moiety has within conjugative chemistry, the nucleophilic thio-bromo reaction is beginning to make an impact in macromolecular science. Typically, a base such as triethylamine is used to deprotonate the thiol, which can then efficiently react with a-bromoesters in a thio-etherification reaction. 

As part of an initial model study, poly(methyl acrylate) prepared via RAFT polymerization in the presence of a conventional RAFT agent (bearing no bromide functionality) was 

An additional interesting observation is that the thio-bromo reaction is kinetically favored over the competing disulfide formation that must always be considered in such systems. The thio-bromo click reaction is obviously very convenient in that it makes use not only of readily available materials, but also some of the most common end groups encountered in modern polymer chemistry. It therefore has the potential to become a valuable addition to the click chemistry toolbox. 

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A,3 Thiol-Yne and Thio-Bromo Chemistry for the Synthesis of Hyperbranched Polymers... 

Rosen, B.M., Lligadas, G., Hahn, C., and Percec, V. (2009a) Synthesis of dendrimers through divergent iterative thio-bromo Click chemistry. Journal of Polymer Science Part A-Polymer Chemistry, XI, 3931. 

Xu, J., Tao, L., Boyer, C. et al. (2010) Combining thio-bromo click chemistry and RAFT polymerization a powerful tool for preparing functionalized multiblock and hyperbranched polymers. Macromolecules. 43,20. 

Until now, thio-bromo click chemistry has only been used for the synthesis of dendrimers and hyperbranched polymers. Without any doubt, further research will lead to other complex architectures, such as dendronized polymers, dendrigrafts and unsymmetrical dendrimers. 

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