Synthesis of 4‐silaspiro[3.4]octa‐1,5‐diene derivatives: hybrid spiro compounds |
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| Authors: | Ezzat Khan Bernd Wrackmeyer Rhett Kempe Germund Glatz |
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| Affiliation: | 1. Department of Chemistry, University of Malakand, Chakdara, Dir (Lower), Khyber Pakhtunkhwa, Pakistan;2. Anorganische Chemie II, Universit?t Bayreuth, Bayreuth, Germany |
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| Abstract: | Trialkynyl(vinyl)silanes CH2?CH? Si(C?C? R)3 (R = Bu, Ph, p‐tolyl) were prepared and treated with 9‐borabicyclo[3.3.1]nonane (9‐BBN). Consecutive 1,2‐hydroboration and intramolecular 1,1‐carboboration reactions (each requires different reaction conditions) were studied. 1,2‐Hydroboration of the Si? vinyl group takes place at ambient temperature (23°C in tetrahydrofuran), followed by intramolecular 1,1‐vinylboration to give 1‐silacyclopent‐2‐ene derivatives, bearing still two alkynyl functions at the silicon atom. Further treatment with a second equivalent of 9‐BBN affords 1‐alkenyl‐1‐(alkynyl)‐1‐silacyclopent‐2‐ene derivatives. These undergo intramolecular 1,1‐vinylboration to give 4‐silaspiro[3.4]octa‐1,5‐dienes bearing the boryl groups at 2 and 6 positions. Protodeborylation of all new compounds (intermediates and final products) using acetic acid in slight excess afforded corresponding silanes including spirosilanes. All compounds were characterized using multinuclear NMR spectroscopy (1H, 11B, 13C, 29Si) in solution state. Solid‐state structures for one of the trialkynyl(vinyl)silanes (R = p‐tolyl) and one of the 1‐silacyclopent‐2‐ene derivatives (R = Ph) were confirmed using X‐ray diffraction. Copyright © 2015 John Wiley & Sons, Ltd. |
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| Keywords: | alkynyl(vinyl)silanes hydroboration carboboration protodeborylation spirosilanes |
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