Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoudai-katsura, Nishikyo, Kyoto 615-8510, Japan.
J Am Chem Soc. 2010 Dec 15;132(49):17452-8. doi: 10.1021/ja104439w. Epub 2010 Nov 17.
About 40 years have passed since methylene dizinc reagent was discovered as a substitute for Wittig reagent. Density functional theory (DFT) calculations have been performed to understand the reaction pathways of methylenation of carbonyl compounds with bis(iodozincio)methane. The present computational/theoretical study concluded that the methylenation reaction with gem-dizinc reagent proceeds as a two-step reaction, that is, methylene addition (RDS) and olefination. In the first step, the nucleophilic attack of the CH2 group enhanced by two Zn proceeds under the assistance of the electrophilic activation of the carbonyl group with the Zn atom. In the second step, the olefination is facilitated by both Zn atoms of the gem-dizinc reagent without an electron transfer process.
自从发现亚甲基二锌试剂作为维蒂希试剂的替代品以来，已经过去了大约 40 年。本文通过密度泛函理论（DFT）计算，研究了双（碘代锌）甲烷与羰基化合物的甲叉化反应途径。本计算/理论研究的结论是，偕二锌试剂的甲叉化反应是一个两步反应，即亚甲基加成（RDS）和烯烃化。在第一步中，在羰基基团的 Zn 原子的亲电活化的辅助下，两个 Zn 原子增强的 CH2 基团进行亲核进攻。在第二步中，不需要电子转移过程，偕二锌试剂的两个 Zn 原子促进了烯烃化。
