Procuranti Barbara, Connon Stephen J
Centre for Synthesis and Chemical Biology, School of Chemistry, University of Dublin, Trinity College, Dublin 2, Ireland.
Org Lett. 2008 Nov 6;10(21):4935-8. doi: 10.1021/ol802008m. Epub 2008 Oct 7.
Simple pyridinium salt derivatives have been (rather unexpectedly) shown to promote highly efficient acetalization reactions of both aldehydes and ketones at ambient temperature. The optimum catalyst is aprotic, yet it can promote the formation of benzaldehyde dimethyl acetal at 0.1 mol % loading more efficiently than a protic Brønsted acid catalyst with a pKa of 2.2. The process is of wide scope with respect to both the nucleophilic and electrophilic components, and the ionic catalyst can be readily recovered by precipitation and reused without loss of activity.
简单吡啶盐衍生物已（相当出人意料地）被证明能在室温下促进醛和酮的高效缩醛化反应。最佳催化剂是质子惰性的，但在0.1 mol%的负载量下，它比pKa为2.2的质子布朗斯特酸催化剂更有效地促进苯甲醛二甲基缩醛的形成。该过程在亲核和亲电组分方面都具有广泛的适用范围，并且离子催化剂可以通过沉淀轻易回收并重复使用而不会损失活性。
