Transition Metal-Free Regio- and Stereo-Selective trans Hydroboration of 1,3-Diynes: A Phosphine-Catalyzed Access to (E)-1-Boryl-1,3-Enynes |
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| Authors: | Swetha Jos Connor Szwetkowski Dr. Carla Slebodnick Robert Ricker Ka Lok Chan Wing Chun Chan Prof. Dr. Udo Radius Prof. Dr. Zhenyang Lin Prof. Dr. Todd B. Marder Prof. Dr. Webster L. Santos |
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| Affiliation: | 1. Department of Chemistry, Virginia Tech, Blacksburg, Virginia, United States;2. Institute of Inorganic Chemistry, Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Germany;3. Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China |
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| Abstract: | We report a transition metal-free, regio- and stereo-selective, phosphine-catalyzed method for the trans hydroboration of 1,3-diynes with pinacolborane that affords (E)-1-boryl-1,3-enynes. The reaction proceeds with excellent selectivity for boron addition to the external carbon of the 1,3-diyne framework as unambiguously established by NMR and X-ray crystallographic studies. The reaction displays a broad substrate scope including unsymmetrical diynes to generate products in high yield (up to 95 %). Experimental and theoretical studies suggest that phosphine attack on the alkyne is a key process in the catalytic cycle. |
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| Keywords: | enediyne enyne hydroboration organocatalytic stereoselective |
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