Ethanol, ring-opening polymerization catalysts

Polymer 149, prepared by ring-opening polymerization (ROMP) of the corresponding functionalized norbornene, provides a clear illustration of the potential of this kind of materials. This resin catalyzes (12% molar) the reaction of linear aliphatic aldehydes with unsaturated ketones to provide 1,4-dicarbonyl compounds (153, Scheme 10.23) and was used for four consecutive cycles without any detectable decrease in performance [358]. A similar dimethylthiazolium structure supported on 2% cross-linked PS-DVB (150) was studied as catalyst for the acyloin condensation of a large variety of aldehydes [364], Catalyst 150 is used in 10 mol.% and the reaction takes place in ethanol at room temperature, with triethylamine as the base, to afford the corresponding a-hydroxyketones in excellent yields. Remarkably, the catalyst can be reused 20 times without losing its activity. 

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