Sulfinyl precursor route

Recently, a new synthetic route toward PPV and its derivatives has been reported in which the monomer is polymerized toward a dithiocarbamate precursor polymer by the additimi of a strong base. The corresponding conjugated polymer is obtained via a heart treatment of the precursor polymer. This dithiocarbamate precursor route represents a compromise between several straightforward but sometimes troublesome precursor routes and the more complex sulfinyl precursor route [134]. 

Vanderzande, DJ.M., Marin, G.B., 2011. Kinetic Monte Carlo modeling of the sulfinyl precursor route for poly (p-phenylene vinylene) synthesis. Macromolecules 44, 8716-8726. 

The sulfinyl precursor route is distinct from other radical/anionic polymerizations as the monomer is nonsymmetric (Scheme 7.2d). This means the polymer synthesis is more controlled and it is possible to achieve regiore-gular PPV materials. However, the monomers are more difficult to prepare (Scheme 7.3). Starting from the bis-sulfonium monomer 20, reaction with one... 

The first decision in choosing a synthetic method for a PPV material is the way in which the material will be processed (Scheme 7.8). The precursor routes will enable the preparation of solvent-resistant and more durable thin films of PPV. This is particularly desirable if a multilayer device structure is required for the application. When choosing different precursor methods, it is important to assess the criteria of the application. Most precursor methods involve a thermal elimination step to convert the precursor polymer to the PPV material. Sul-fonium precursors require higher-temperature elimination compared to sulfinyl precursors. This makes the sulfinyl route compatible with deposition on plastic substrates. Another factor to consider in precursor methods is the nature of the elimination byproducts. Sulfonium precursors convert to PPV with elimination of acids, such as HCl or HBr, which has been shown to be detrimental to device performance. Xanthate and dithiocarbamate routes involve the elimination of amine and CO2 and CS2, respectively. 

Sulfinyl or Louwet-VaruJerainde Precursor Route. The development of sulfinyl precursor polymers by Louwet et al. [996-998] has overcome many of the drawbacks of the previous precursor routes. 

Uzan and co-workers311 have reported an alternative route for the preparation of pyranose and furanose c/.v-l,2-fused oxazolidine-2-thiones that uses 1,2-O-sulfinyl sugar derivatives (169) as precursors. After treatment with sodium thiocyanate in DMF at 80°C, the bicyclic thiocarbamales (172) were isolated in 60-90% yield. The proposed mechanism involves formation of a -configured thiocyanate (170) that isomerizes to the a-isothiocyanate derivative (171) under the reaction conditions (Scheme 49). 

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