Polymer-Supported Ionic-Liquid-Catalyzed Synthesis of 1,2,3,4-Tetrahydro- 2-oxopyrimidine-5-carboxylates via Biginelli Reaction

The Biginelli reaction between an aromatic aldehyde, ethyl acetoacetate, and urea – catalyzed by polymer-supported, re-usable, room-temperature ionic liquids (RTIL) such as 1b – was shown to efficiently proceed in glacial AcOH at 100° to afford the corresponding pyrimidine-5-carboxylates 3 in yields up to 99% within 2 4;h (Table 4;2). The catalyst(s) could be reused at least five times, basically without loss of activity, which makes this transformation not only straight-forward, but also considerably less expensive compared to methods involving classical RTIL catalysts.