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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| Institution: | 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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