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Updated: Mar 5, 2026
Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
Alkene-Carbene Isomerization induced by Borane: Access to an Asymmetrical Diborene
Wei Lu1, Yongxin Li1, Rakesh Ganguly1
1Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, and ‡NTU-CBC Crystallography Facility, Nanyang Technological University , 637371, Singapore.
Abstract:
A 2,3-dihydro-1H-1,2-azaborole derivative 2 was converted to a cyclic (alkyl) (amino)carbene (cAAC) via 1,2-hydrogen migration triggered by boranes to afford cAAC-borane adducts. This procedure allowed us to develop an asymmetrical diborene cAAC·(Br)B═B(Br)·IDip 6, which was isolated and fully characterized. The 11B NMR spectrum, X-ray diffraction analysis and computational studies indicate that π-electrons on the central B2 moiety in 6 are unequivalently distributed, and thus polarized. A complete scission of the B═B double bond in 6 was achieved by the treatment with an isonitrile, which led to the formation of a base-stabilized B,N-containing methylenecyclopropane 7.
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