Santos Leonardo S, Rosso Giovanni B, Pilli Ronaldo A, Eberlin Marcos N
Laboratory of Asymmetric Synthesis, Chemistry Institute of Natural Resources, Universidad de Talca, P.O. Box 747, Talca, Chile.
J Org Chem. 2007 Jul 20;72(15):5809-12. doi: 10.1021/jo062512n. Epub 2007 Jun 22.
On-line monitoring of Stille reactions was performed via direct infusion electrospray ionization mass spectrometry (ESI-MS) and its tandem version (ESI-MS/MS). When operated in the positive ion mode, ESI(+)-MS was able to transfer, directly from solution to the gas phase, the species involved in all main steps of a Stille reaction, that is, the catalytically active palladium species Pd(PPh3)2, in its molecular ion form as well as the key cationic Pd(II) intermediates, including cyclic IPd-(CH2CH)Sn species. When searching for anionic species, ESI(-)-MS monitoring showed I- as the only anion detectable in the reaction medium. A detailed catalytic cycle for a Stille reaction was elaborated in which reaction intermediates and the previously elusive catalytically active Pd(0) species are shown in association with the respective ionic species intercepted by ESI-MS and further characterized by ESI-MS/MS.
通过直接进样电喷雾电离质谱（ESI-MS）及其串联模式（ESI-MS/MS）对施蒂勒反应进行在线监测。当以正离子模式运行时，ESI(+)-MS能够将施蒂勒反应所有主要步骤中涉及的物种直接从溶液转移到气相，即催化活性钯物种Pd(PPh3)2，以其分子离子形式以及关键的阳离子Pd(II)中间体，包括环状IPd-(CH2CH)Sn物种。在寻找阴离子物种时，ESI(-)-MS监测显示I-是反应介质中唯一可检测到的阴离子。阐述了施蒂勒反应的详细催化循环，其中反应中间体和之前难以捉摸的催化活性Pd(0)物种与ESI-MS截获的相应离子物种相关联，并通过ESI-MS/MS进一步表征。
