Ludwig-Maximilians-Universität München, Department Chemie, Butenandtstrasse 5-13, Haus F, 81377, München, Germany.
Angew Chem Int Ed Engl. 2016 Aug 22;55(35):10502-6. doi: 10.1002/anie.201603923. Epub 2016 Jul 19.
Readily prepared allylic zinc halides undergo SN 2-type substitutions with allylic bromides in a 1:1 mixture of THF and DMPU providing 1,5-dienes regioselectively. The allylic zinc species reacts at the most branched end (γ-position) of the allylic system furnishing exclusively γ,α'-allyl-allyl cross-coupling products. Remarkably, the double bond stereochemistry of the allylic halide is maintained during the cross-coupling process. Also several functional groups (ester, nitrile) are tolerated. This cross-coupling of allylic zinc reagents can be extended to propargylic and benzylic halides. DFT calculations show the importance of lithium chloride in this substitution.
易于制备的烯丙基锌卤化物在 THF 和 DMPU 的 1:1 混合物中与烯丙基溴进行 SN2 型取代，可选择性地提供 1,5-二烯。烯丙基锌物种在烯丙基体系的最支化端（γ-位）反应，仅提供γ,α'-烯丙基-烯丙基交叉偶联产物。值得注意的是，在交叉偶联过程中保持了烯丙基卤化物的双键立体化学。此外，一些官能团（酯基、腈基）也能耐受。这种烯丙基锌试剂的交叉偶联可以扩展到炔丙基和苄基卤化物。DFT 计算表明氯化锂在该取代反应中的重要性。
