Iridium-catalyzed Vinylic C–H Borylation of Cyclic Vinyl Ethers by Bis(pinacolato)diboron
作者:Takao Kikuchi、Jun Takagi、Tatsuo Ishiyama、Norio Miyaura
DOI:10.1246/cl.2008.664
日期:2008.6.5
Vinylic C–H borylation of cyclic vinyl ethers by bis(pinacolato)diboron was effectively catalyzed by iridium complexes comprised of 1/2[Ir(OMe)(cod)]2 and 4,4′-di-tert-butyl-2,2′-bipyridine in hexane or octane to give the corresponding vinylboron compounds in good yields. The reaction of 1,4-dioxene occurred even at room temperature, whereas the reactions of dihydropyran and dihydrofuran derivatives required a temperature above 80 °C. Although dihydropyran and dihydrofuran themselves produced regioisomeric mixtures of α- and β-borylated products, similar substrates possessing substituents at the γ-position selectively underwent borylation at the α-position.
由 1/2[Ir(OMe)(cod)]2 和 4,4′-二叔丁基-2,2′-联吡啶组成的铱配合物在己烷或辛烷中有效催化了双(频哪醇)二硼酸环乙烯基醚的乙烯基 C-H 硼酸化反应,从而以良好的收率得到了相应的乙烯基硼化合物。1,4-dioxene 的反应甚至可以在室温下进行,而二氢吡喃和二氢呋喃衍生物的反应则需要 80 °C 以上的温度。虽然二氢吡喃和二氢呋喃本身会产生α-和β-硼化产物的区域异构混合物,但在γ-位上具有取代基的类似底物会选择性地在α-位上发生硼化反应。