Dissertation/ Thesis
Stereodivergente ionische und radikalische Silylzinkierungen von α-heteroatomsubstituierten C–C-Dreifachbindungen ; Stereodivergent ionic and radical silylzincations of α-heteroatom-substituted C–C triple bonds
| العنوان: | Stereodivergente ionische und radikalische Silylzinkierungen von α-heteroatomsubstituierten C–C-Dreifachbindungen ; Stereodivergent ionic and radical silylzincations of α-heteroatom-substituted C–C triple bonds |
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| المؤلفون: | Fopp, Carolin |
| المساهمون: | Oestreich, Martin, Technische Universität Berlin, Wegner, Hermann A. |
| سنة النشر: | 2018 |
| المجموعة: | TU Berlin: Deposit Once |
| مصطلحات موضوعية: | 547 Organische Chemie, Silylmetallierung, Silylzinkierung, Vinylsilane, silylmetalation, silylzinc reagents, vinyl silane |
| الوصف: | The present work investigates the stereodivergent silylzincation of α-heteroatom-substituted C–C triple bonds. In close collaboration with the group of PEREZ-LUNA, α-nitrogen-, α-phosphor-, α-oxygen-, and α-sulfur-substituted terminal alkynes were reacted with (Me3Si)3SiH/Et2Zn or [(Me3Si)3Si]2Zn/Et2Zn as well as (Me2PhSi)2Zn∙4LiCl. The addition of these reagents to the C–C triple bonds generally occurred with high β selectivity, and the diastereoselectivity could be controlled: With (Me3Si)3SiH/Et2Zn or [(Me3Si)3Si]2Zn/Et2Zn, a novel trans-selective addition to β-(Z)-vinylsilanes was observed whereas with (Me2PhSi)2Zn∙4LiCl a cis-silylzincation to the corresponding β-(E)-vinylsilanes occurred. Furthermore, the silylzincation was combined with a subsequent one-pot copper-mediated electrophilic substitution of the intermediate C(sp2)–Zn bond. The functionalization reactions were performed with different carbon- or tin-based electrophiles and showed a dependence on the disilylzinc reagent: The silylzincation with (Me3Si)3SiH/Et2Zn or [(Me3Si)3Si]2Zn/Et2Zn tolerated all electrophiles and led, under moderate to excellent stereocontrol, to the corresponding trisubstituted β-(Z)-vinylsilanes in moderate to high yields. Conversely, only α-nitrogen-substituted alkynes were able to react with (Me2PhSi)2Zn∙4LiCl and different carbon-based electrophiles. Due to the steric hindrance imparted by the cis-silicon group of the α-zinc-β-silyl alkene intermediate, electrophilic substitution with tin-based electrophiles did not lead to the desired products. α-Phosphor- or α-sulfur-substituted alkynes reacted in the sequential silylzincation–copper(I)-mediated electrophilic substitution protocol only with allyl bromide whereas α-oxygen-substituted alkynes failed to react. The stereodivergence was induced by the different nature of the disilylzinc reagents. The Si–Zn bond of [(Me3Si)3Si]2Zn is cleaved homolytically with traces of oxygen leading to a stepwise radical-based trans-selective silylmetalation. In contrast, the ... |
| نوع الوثيقة: | doctoral or postdoctoral thesis |
| وصف الملف: | application/pdf |
| اللغة: | German |
| Relation: | https://depositonce.tu-berlin.de/handle/11303/7386; http://dx.doi.org/10.14279/depositonce-6635 |
| DOI: | 10.14279/depositonce-6635 |
| الاتاحة: | https://depositonce.tu-berlin.de/handle/11303/7386 https://doi.org/10.14279/depositonce-6635 |
| Rights: | http://rightsstatements.org/vocab/InC/1.0/ |
| رقم الانضمام: | edsbas.1E68B912 |
| قاعدة البيانات: | BASE |
| DOI: | 10.14279/depositonce-6635 |
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