Umpolung of B-H Bonds by Metal-Ligand Cooperation with Cyclopentadienone Iridium Complexes.
Umpolung of B-H Bonds by Metal-Ligand Cooperation with Cyclopentadienone Iridium Complexes.
复制标题
DOI：
10.1002/ange.202011322
复制
发表时间：
2020-11
影响因子：
--
通讯作者：
T. Higashi;Shuhei Kusumoto;K. Nozaki
中科院分区：
文献类型：
--
作者：
T. Higashi;Shuhei Kusumoto;K. Nozaki
与传统的金属-配体的B-H键协同切割在配体上提供B阳离子和在金属上提供H阴离子相比，本文报道了新型环戊二烯酮铱配合物首次破坏B-H键。对于HBpin（= 4,4,5,5-四甲基-1,3,2-二恶硼烷）和HBdan（= 1,8-萘二胺硼烷），B-H键被切割成金属上的B阴离子和配体中酚氧上的H阳离子。DFT计算表明，烷氧羰基取代的环戊二酮配体在氧化加成B-H键后，促进了Ir-H的脱质子反应，得到了umpolung产物。所生成的硼锂配合物在碱的存在下发生了烯丙基卤化物的硼化反应，显示出硼原子的亲核性质。
Contrastive that the conventional metal-ligand cooperative cleavage of a B-H bond provides a B cation on the ligand and an H anion on the metal, herein we report the first umpolung of B-H bonds by novel cyclopentadienone iridium complexes. For HBpin (= 4,4,5,5-tetramethyl-1,3,2-dioxaborolane) and HBdan (= 1,8-naphthalenediaminatoborane), the B-H bonds were cleaved into a B anion on the metal and an H cation on the phenolic oxygen in the ligand. The mechanistic investigation by DFT calculations revealed that the alkoxycarbonyl-substituted cyclopentadienone ligand facilitated the deprotonation from Ir-H after oxidative addition of the B-H bond to give the umpolung product. The generated boryliridium complex was found to undergo borylation of allyl halide in the presence of base to show nucleophilic nature of the boron atom.