trifluoroacetaldehyde ethyl hemiacetal (1) with ketones or aldehydes was described. In the presence of 20 mol % of pyrrolidine, the reaction proceeded smoothly at room temperature to afford the aldol products in good to excellent yields (up to 95%). Pyrrolidine showed a much higher catalytic activity than piperidine in the reaction with less reactive ketones. GC analysis clearly indicated that the catalyst and the
描述了
吡咯烷催化的三
氟乙醛乙基
半缩醛(1)与酮或醛的醛醇缩合反应。在20mol%的
吡咯烷的存在下,反应在室温下顺利进行,以良好至优异的产率(高达95%)提供醛醇产物。在反应性较低的酮反应中,
吡咯烷比
哌啶显示出更高的催化活性。GC分析清楚地表明,反应期间催化剂和烯胺中间体保持在极低的浓度。基于这些观察,我们认为烯胺的形成将是催化醛醇缩合反应的决定速率的步骤。此外,不对称醛醇缩合反应1 还讨论了由脯
氨酸衍
生物催化的
环己酮的合成。