Mechanism and Scope of the Base‐Induced Dehalogenation of (E)‐Diiodoalkenes
Mechanism and Scope of the Base‐Induced Dehalogenation of (E)‐Diiodoalkenes
复制标题
(E)-二碘烯烃的碱诱导脱卤反应的机理和范围
DOI：
10.1002/ejoc.201402992
复制
发表时间：
2015
影响因子：
2.8
通讯作者：
N. Goroff
中科院分区：
文献类型：
--
作者：
Daniel Resch;C. Lee;Siew Yoong Tan;Liang Luo;N. Goroff
在非常温和的条件下，一系列的亲核试剂已诱导碘从(E)-二碘烯烃中消除，生成炔烃。碘离子特别有效，在室温下，在极性的非质子溶剂中，可以在不到1小时的时间内完成反应。详细的研究表明，该反应具有双分子极性机理。脱碘反应可在1当量的条件下完成。是亲核试剂的一部分，并与亚化学计量的脱碘剂部分催化。对化学计量碘诱导的反应的动力学分析表明，整个反应为准一级行为。该反应表现出强烈的溶剂效应，在质子性溶剂中的反应比在极性非质子性溶剂中观察到的反应慢得多。底物(2E)-2，3-二碘丁烯-2-二酸二甲酯对消除或水解表现出了正交性，这取决于所使用的溶剂和亲核剂。这一反应是所有被考察的二碘烯烃的主要途径，对于在有机合成中使用这些底物来说是一个挑战和机会。
A wide range of nucleophiles have induced the elimination of iodine from (E)-diiodoalkenes to form alkynes under surprisingly mild conditions. The iodide anion is particularly efficient, and can drive the reaction to completion in less than 1 hour at room temperature in a polar aprotic solvent. Detailed investigations have suggested the reaction has a bimolecular polar mechanism. The deiodination reaction can be driven to completion with 1 equiv. of nucleophile and is partially catalytic with substoichiometric amounts of deiodinating reagent. Kinetic analysis of the stoichiometric iodide-induced reaction indicated an overall pseudo-first-order behavior. The reaction exhibited strong solvent effects, with much slower reactions observed in protic solvents than in polar aprotic solvents. The substrate dimethyl (2E)-2,3-diiodobutene-2-dioate demonstrated orthogonal reactivity for either elimination or hydrolysis, depending on the solvent and nucleophile used. This reaction is a major pathway for all the diiodoalkenes examined, and represents a challenge and an opportunity for using these substrates in organic synthesis.