水介质中无催化剂下醛酮与活泼亚甲基化合物的缩合反应

报道了水相中无催化剂下各种羰基化合物与活泼亚甲基化合物的Knoevenagel缩合反应. 芳香醛与活泼亚甲基化合物如丙二腈、氰基乙酸乙酯、氰基乙酰胺的缩合在室温下即能顺利进行, 获得了很高的收率; 而对于杂环芳醛、α,β-不饱和的醛以及脂肪醛与活泼亚甲基化合物的缩合, 需在50～65 ℃下进行, 也取得了很高的收率; 对于脂肪酮、芳香酮以及二元醛与丙二腈的缩合在75～85 ℃下也能顺利地进行, 获得中等以上的收率. 反应简单、高效而且对环境友好.

Uncatalyzed Condensation of Active Methylene Compounds with Aldehydes or Ketones in Aqueous Medium

The Knoevenagel condensations of various carbonyl compounds with active methylene compounds were reported in water medium without adding any catalyst. The condensation of aromatic aldehydes with active methylene compounds like malononitrile, cyanoacetamide and ethyl cyanoacetate has been found to proceed very efficiently at room temperature giving excellent yields, but the condensation of heteroaromatic, α,β-unsaturated and aliphatic aldehydes with active methylene compounds proceeded smoothly in 50～65 ℃ with good yields and the reactions of aromatic, aliphatic ketones as well as p-phthalaldehyde with malononitrile also proceeded in 75～85 ℃ with moderate yields. The work-up procedure is simple, efficient and environment-friendly.