Asymmetric Catalysis with Silicon‐Based Cuprates: Enantio‐ and Regioselective Allylic Substitution of Linear Precursors |
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Authors: | Alexander Hensel Prof?Dr Martin Oestreich |
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Institution: | Institut für Chemie, Technische Universit?t Berlin, Strasse des 17. Juni 115, 10623 Berlin (Germany) http://www.organometallics.tu‐berlin.de |
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Abstract: | An enantio‐ and regioselective allylic silylation of linear allylic phosphates that makes use of catalytically generated cuprate‐type silicon nucleophiles is reported. The method relies on soft bis(triorganosilyl) zincs as silicon pronucleophiles that are prepared in situ from the corresponding hard lithium reagents by transmetalation with ZnCl2. With a preformed chiral N‐heterocyclic carbene–copper(I) complex as catalyst, exceedingly high enantiomeric excesses are achieved. The new method is superior to existing ones using a silicon–boron reagent as the source of the silicon nucleophile. |
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Keywords: | allylic substitution asymmetric catalysis copper silicon zinc |
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