Small but Effective: Copper Hydride Catalyzed Synthesis of α-Hydroxyallenes


  • Financial support by the Deutsche Forschungsgemeinschaft, the Fonds der Chemischen Industrie (to N.K.), and the National Science Foundation (CHE-0550232, to B.H.L.) is gratefully acknowledged. We thank Prof. Dr. F. Glorius (University of Marburg) for providing a sample of carbene precursor 1 f, and Dr. A. Hoffmann-Röder (University of Mainz) for fruitful discussions.


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Mild and efficient: The copper hydride catalyzed diastereoselective SN2′ reduction of propargyl oxiranes provides α-hydroxyallenes bearing various functional groups (ethers, esters, alcohols; see scheme, PMHS=polymethylhydridosiloxane). The best results were obtained with a copper hydride catalyst and an N-heterocyclic carbene ligand. The resulting allenes are useful substrates, as they undergo, for example, regio- and chemoselective cycloisomerization to give 2,5-dihydrofurans.