X-Ray crystallographic and 13C nuclear magnetic resonance studies of 3,4,5,6-tetrahydro-2H-1,3,4-oxadiazin-2-ones derived from ephedrine and pseudoephedrine
作者:Shawn R Hitchcock、George P Nora、David M Casper、Michael D Squire、Christopher D Maroules、Gregory M Ferrence、Lisa F Szczepura、Jean M Standard
DOI:10.1016/s0040-4020(01)00967-x
日期:2001.12
2S)-pseudoephedrine have been synthesized and their conformational properties have been examined. The ephedrine heterocycles 5–7a appear to favor one set of equilibrating conformers while the pseudoephedrine heterocycles 5–7b exist as multiple conformers at room temperature. The observed conformational behavior of these heterocycles is attributed to allylic strain and a gauche effect arising from the torsional energy
合成了由(1 R,2 S)-麻黄碱和(1 S,2 S)-伪麻黄碱衍生的3,4,5,6-四氢-2 H -1,3,4-恶二嗪-2-酮,并合成了它们构象性质已被检查。麻黄碱杂环5 -图7a显示以有利于一组平衡构象异构体,而假麻黄碱杂环5 - 7b中存在作为在室温下的多个构象异构体。观察到的这些杂环的构象行为归因于烯丙基应变和N 3-和N 4的孤对电子之间的扭转能垒引起的变态效应。-氮。