Synthesis of Base-Stabilized Hydrido(hydroborylene)tungsten Complexes and Their Reactions with Terminal Alkynes To Give η3-Boraallyl Complexes
Synthesis of Base-Stabilized Hydrido(hydroborylene)tungsten Complexes and Their Reactions with Terminal Alkynes To Give η3-Boraallyl Complexes
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DOI：
10.1021/acs.organomet.7b00723
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发表时间：
2017-12-25
期刊：
影响因子：
2.8
通讯作者：
Tobita, Hiromi
中科院分区：
文献类型：
--
作者：
Hui, Zeping;Watanabe, Takahito;Tobita, Hiromi
甲基的反应（吡啶）钨配合物Cp*（CO）（2）W（py）Me与硼烷-NHC（NHC = N-杂环卡宾;（IMe）-I-Me，（TPr）-T-Me）（（IMe）-I-Me = 1，3，4，5-四甲基咪唑-2-亚基，5-二甲基咪唑-2-亚基）加合物得到了NHC稳定的双氢吲哚（亚氢硼基）钨络合物Cp*（CO）（2）W（H）-（BH中心点NHC）（la：NHC =（IMe）-I-Me，lb：NHC =（IPr）-I-Me-Pr-i），其为深棕色晶体，高产率，伴随着吡啶和甲烷的释放。X射线晶体结构分析表明，Ib的W-B键是由一个双氧配体桥连的。1a、B与苯乙炔在室温下反应，通过新型的炔三键硼氢化反应，分别得到NHC稳定的eta（3）-硼烯丙基配合物2a、B：即，氢和亚硼基的加成。Ia与3-丁炔-2-酮的反应还导致三键而不是C= O双键的硼氢化，得到η（3）-硼杂烯丙基络合物3。在1a与三甲基硅基乙炔的反应中，通过炔三键的碳硼化，形成1-氧代-4-硼丁烯基络合物4作为初级产物。4在环境温度下的随后缓慢反应导致形成比率为5：4的η（3）-硼杂烯丙基络合物5和碳炔络合物6。在所有这些反应中，区域选择性硼化的末端碳的炔观察。
Reaction of the methyl(pyridine)tungsten complex Cp*(CO)(2)W(py)Me with borane-NHC (NHC = N-heterocyclic carbene; (IMe)-I-Me, (TPr)-T-Me) ((IMe)-I-Me = 1,3,4,5-tetramethylimidazol-2-ylidene, (IPr)-I-Me-Pr-i = l,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) adducts gave the NHC-stabilized hydrido(hydroborylene)tungsten complexes Cp*(CO)(2)W(H)-(BH center dot NHC) (la: NHC = (IMe)-I-Me, 1b: NHC = (IPr)-I-Me-Pr-i) as dark brown crystals in high yields accompanied by liberation of pyridine and methane. X-ray crystal structure analysis revealed that the W-B bond of Ib is bridged by a hydrido ligand. Reactions of 1a,b with phenylacetylene at room temperature afforded NHC-stabilized eta(3)-boraallyl complexes 2a,b, respectively, through a new type of hydroboration of the alkyne triple bond: i.e., addition of a hydrogen and a borylene. Reaction of la with 3-butyn-2-one also led to hydroboration of the triple bond, not the C=0 double bond, to give eta(3)-boraallyl complex 3. In the reaction of 1a with (trimethylsilyl)acetylene, 1-oxo-4-borabutenyl complex 4 was formed as a primary product through carboboration of the alkyne triple bond. The subsequent slow reaction of 4 at ambient temperature resulted in the formation of eta(3)-boraallyl complex 5 and carbyne complex 6 in the ratio of 5:4. In all of these reactions, regioselective boration of the terminal carbon of alkynes was observed.