Abstract

Reactions of mixed phosphonium-iodonium ylides with nitriles and acetylenes allow for the synthesis of not easily accessible and novel heterocyclic compounds in a simple, one-pot, metal-free system. The results of the mechanistic investigation of the reaction of the phosphonium-iodonium ylides with acetylenes by means of spectrophotometry, EPR and NMR spectroscopy are discussed in this review. This investigation allows to account for unusual regularities of these reactions: induction time, acid catalysis, chemically induced dynamic nuclear polarization effect (CIDNP) observed in several systems, and others. The radical character of the initiation of the reaction as a result of acid catalysis of the ylides decomposition on radicals and the participation of radical intermediates in the formation of all target products have been unambiguously established. The mechanism of generation of radical pairs in CIDNP was suggested, and the role of microheterogeniety of the ylide solutions in methylene chloride was substantiated. On the basis of the study of the reaction mechanism, the conditions for the increase in the yields of new heterocyclic compounds can be optimized.

中文翻译：

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混合的磷-碘鎓叶立德与乙炔反应的显着机理

摘要

混合的-碘鎓碘化物与腈和乙炔的反应可以在一个简单的无罐无金属系统中合成不易获得的新型杂环化合物。本文讨论了通过分光光度法，EPR和NMR光谱对phospho-碘鎓碘化物与乙炔反应进行机理研究的结果。这项研究可以解释这些反应的异常规律：诱导时间，酸催化作用，在几个系统中观察到的化学诱导的动态核极化效应（CIDNP）等。明确地确定了由于自由基对自由基分解产生的酸催化作用而引发反应的自由基特征，并且自由基中间体参与了所有目标产物的形成。提出了在CIDNP中产生自由基对的机制，并证实了叶立德溶液在二氯甲烷中的微异质性作用。在研究反应机理的基础上，可以优化增加新杂环化合物的产率的条件。