Department of Chemistry, York University, 4700 Keele Street, Toronto, ON, M3J 1P3 (Canada) http://www.yorku.ca/organ/
Angew Chem Int Ed Engl. 2014 Apr 22;53(17):4386-9. doi: 10.1002/anie.201400459. Epub 2014 Mar 26.
The role of halide salt additives has been investigated in the Negishi reaction involving aryl zinc reagents. Diarylzincs readily transmetallate to Pd in relatively non-polar media (e.g., THF) with zero salt present and coupling proceeds. Arylzinc halides (ArZnX) fail to couple in THF without salt, but do couple with it. However, unlike alkylzincs that form higher-order zincates in order to facilitate transmetallation, all that is required with arylzincs in an increase in solvent dielectric as even ZnX2 works as an additive, which completely terminates alkylzinc coupling.
卤化物盐添加剂在涉及芳基锌试剂的 Negishi 反应中的作用已经得到了研究。二芳基锌在相对非极性介质（例如 THF）中很容易与 Pd 发生转金属化，在没有盐存在的情况下偶联反应也能进行。芳基锌卤化物（ArZnX）在没有盐的情况下不能在 THF 中偶联，但加入盐后可以偶联。然而，与形成更高阶锌化物以促进转金属化的烷基锌不同，芳基锌只需要增加溶剂的介电常数即可，即使是 ZnX2 也可以作为添加剂，它完全终止了烷基锌的偶联。
