The intramolecularcarbolithiation of a series of propargylic ethers has been performed to evaluate the influence of the terminal substituent on the efficiency and the stereochemical outcome of the cyclization. Our results show that only 5-exo-dig cyclizations are observed, and dihydrobenzofurans are obtained exclusively. Depending on the nature of the terminal substituent, two cases can be considered
已经进行了一系列炔丙醚的分子内碳锂化,以评估末端取代基对环化效率和立体化学结果的影响。我们的结果表明,仅观察到 5-exo-dig 环化,并且仅获得了二氢苯并呋喃。根据末端取代基的性质,可以考虑两种情况。如果炔烃碳原子携带的末端取代基本身是碳原子,则只要末端炔丙基位置带有配位元素并且至少是二取代的,就可以发生环化。当环化发生时,它遵循反碳石化途径,从而导致环外双键的 E 异构体。仅在一种情况下(Ph)是回收的所得烯烃的E和Z异构体的混合物。如果调节环化条件,炔烃直接被 S 或 Si 取代,也可以发生环化。在三甲基甲硅烷基取代基的情况下,观察到顺式碳锂化。如果双键被恢复,在大多数情况下,在环外位置,产物可以直接芳构化为 SPh 取代的底物 24。此外,在后两种情况下,当进行乙烯基锂中间体的烷基化时,双键的异构化似乎是瞬间的。
Reaction of trimethylsilylpropargyl phenyl ether with organoboranes in the presence of sodium methoxide
作者:Toshinobu Yogo、Junji Koshino、Akira Suzuki
DOI:10.1016/s0040-4039(01)86216-x
日期:1979.1
Silylallenes () are selectively prepared from trimethylsilylpropargyl phenyl ether and trialkylboranes by treatment with sodiummethoxide.
通过用甲醇钠处理,由三甲基甲硅烷基炔丙基苯基醚和三烷基硼烷选择性地制备甲硅烷基亚烷基()。
Regioselective synthesis of highly functionalized alkenylboronates by Cu-catalyzed borylation of propargylic silylalkynes
作者:Yeong Eun Kim、DingXi Li、Jaesook Yun
DOI:10.1039/c5dt00144g
日期:——
Highregioselectivity was achieved in the Cu(I)-catalyzed borylation of internal propargylic alkynes with a silyl substituent to afford multifunctionalized alkenylboron compounds. While both the silyl and propargylic substituents are known to act as directing groups, a N-heterocyclic carbene (NHC)–Cu complex furnished β-vinylboronate products (relative to Si) with high selectivity.
Efficient <i>Z</i>-Selective Semihydrogenation of Internal Alkynes Catalyzed by Cationic Iron(II) Hydride Complexes
作者:Nikolaus Gorgas、Julian Brünig、Berthold Stöger、Stefan Vanicek、Mats Tilset、Luis F. Veiros、Karl Kirchner
DOI:10.1021/jacs.9b09907
日期:2019.10.30
The bench-stable cationic bis(σ-B-H) aminoborane complex [Fe(PNPNMe-iPr)(H)(η2-H2B=NMe2)]+ (2) efficiently catalyzes the semi-hydrogenation of internal alkynes, 1,3-diynes and 1,3-enynes. Moreover, selective incorporation of deuterium was achieved in the case of 1,3-diynes and 1,3-enynes. The catalytic reaction takes place under mild conditions (25oC, 4-5 bar H2 or D2) in 1 h and alkenes were obtained