Regioselective and Stereospecific Dehydrogenative Annulation Utilizing Silylium Ion-Activated Alkenes
Autor: | Masaki Yamamura, Syuhei Yamaguchi, Kunio Mochida, Takayuki Kawashima, Kenichi Nakabayashi, Yuto Yano, Hidekazu Arii |
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Rok vydání: | 2016 |
Předmět: |
Steric effects
Annulation 010405 organic chemistry Chemistry Organic Chemistry Regioselectivity Electrophilic aromatic substitution 010402 general chemistry 01 natural sciences Medicinal chemistry Silane 0104 chemical sciences chemistry.chemical_compound Stereospecificity Yield (chemistry) Silylium ion Organic chemistry |
Zdroj: | The Journal of Organic Chemistry. 81:6314-6319 |
ISSN: | 1520-6904 0022-3263 |
Popis: | Treatment of dialkylbenzylsilanes (1) with trityl tetrakis(pentafluorophenyl)borate (TPFPB) afforded the corresponding silylium ions in equilibrium with their intra- or intermolecular π-complexes, which underwent dehydrogenative annulation with various alkenes to form 1,2,3,4-tetrahydro-2-silanaphthalenes (4) in up to 82% isolated yield. Sterically bulkier substituents on the silicon atom tended to increase the yield of cyclic products 4. The annulation products retained the stereochemistry in cases of the reactions using internal alkenes. The use of diisopropyl(1-naphthyl)silane (2) instead of 1 also resulted in annulation to obtain the 2,3-dihydro-1-sila-1H-phenalene derivatives 6. Electrophilic aromatic substitution at the 8-position was predominant, despite the two potentially reactive positions on the naphthyl group. The steric hindrance of the naphthyl group prevented addition of the cis-alkene to the silylium ion, which would considerably decrease yields of the desired products from 2 compared to those from 1. |
Databáze: | OpenAIRE |
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