Organisch-Chemisches Institut, Universität Münster, Corrensstrasse 40, D-48149 Münster, Germany.
J Org Chem. 2010 Jan 1;75(1):222-5. doi: 10.1021/jo901872a.
An unprecedented cascade of reactions after acid-catalyzed hydrolysis of tert-butyl (2S,5S)-2-tert-butyl-5-(2-fluoroallyl)-3-methyl-4-oxoimidazolidine-1-carboxylate 3a leading to pipecolic acid derivative 5 is presented. The vinylfluoro group is shown to be an acetonyl cation equivalent under acidic conditions. Interestingly, vinylchloro and vinylbromo groups do not show such transformation under the same conditions. The pipecolic acid derivative 5 produced in this way is further used to synthesize (2R,4R,6S)-6-tert-butyl-4-hydroxypiperidine-2-carboxylic acid 9.
呈现了tert-butyl (2S,5S)-2-tert-butyl-5-(2-fluoroallyl)-3-methyl-4-oxoimidazolidine-1-carboxylate 3a 在酸催化水解后前所未有的级联反应，导致哌啶酸衍生物 5 的生成。证明了在酸性条件下，乙烯基氟基团是乙酰丙酮阳离子等价物。有趣的是，在相同条件下，乙烯基氯和乙烯基溴基团不会发生这种转化。以这种方式产生的哌啶酸衍生物 5 进一步用于合成(2R,4R,6S)-6-tert-butyl-4-hydroxypiperidine-2-carboxylic acid 9。
