氟烷基化和氟烷氧基化的研究 23.锌单电子转移引发全氟烷基碘与吡咯的反应

Studies on Fluoroalkylation and Fluoroalkoxylation 23. The Single Electron Transfer Induced Reaction of Perfluoroalkyl Iodides with Pyrrole by Zinc

在二甲亚砜或二甲基甲酰胺中,锌能迅速引发全氟烷基碘(1)与吡咯的反应,生成2-氟烷基吡咯(3);在二氧六环中,主要生成全氟烷基碘的偶合产物5;在乙腈、二乙二醇二甲醚或苯等溶剂中,则同时生成3和5.反应能被对二硝基苯阻止.加入二烯丙基醚能得到氟烷基取代的四氢呋喃衍生物.反应可能经锌单电子转移引发的自由基机理.对溶剂效应作了讨论.

Zinc can induce the reaction of perfluoroalkyl iodides(1) with pyrrole readily to give the regioselective products, 2-perfluoroalkyl pyrrole(3) in DMSO or DMF. However, in dioxane the homo-couple product 5(R_F-R_F) is the main product. This reaction can be suppressed by p-DNB, and afford the five-membered ring compounds in the presence of DAE. All these results indicate that the radical mechanism induced by the single electron transfer from zinc may be involved. The solvent effects are also discussed.