Herold D A, Smith B J, Ross R M, Marquis F, Ayers C R, Wills M R, Savory J
Prostaglandins. 1987 Apr;33(4):599-602. doi: 10.1016/0090-6980(87)90283-8.
A reported method for the preparation of d3-methoxime derivatives as internal standards for prostaglandin assays by gas chromatography-mass spectrometry was evaluated. Sample derivatization resulted in 1.5-86% exchange of the d3-methoxime in a series of prostaglandins. Exchange was minimal when the methoxime was on the 5-membered ring; whereas, acyclic methoximes exhibited extensive exchange. Induced strain energy due to the steric interaction of the hydroxyl group and the C13-C20 alkyl side chain with the gem-dimethoxylamine transition state is offered as an explanation for the unusual stability of PGE2. The use of 18O exchange of the carboxylic acid function is presented as an alternative for the preparation of unavailable labelled eicosanoids.
对一种报告的制备d3 - 甲氧肟衍生物作为前列腺素气相色谱 - 质谱分析内标的方法进行了评估。样品衍生化导致一系列前列腺素中d3 - 甲氧肟有1.5 - 86%的交换。当甲氧肟位于五元环上时交换最小；而无环甲氧肟表现出广泛的交换。羟基与C13 - C20烷基侧链与偕二甲基羟胺过渡态的空间相互作用所诱导的应变能被用来解释PGE2异常的稳定性。提出使用羧酸官能团的18O交换作为制备难以获得的标记类二十烷酸的替代方法。
