Synthesis and Reduction of Sterically Encumbered Mesoionic Carbene‐Stabilized Aryldihaloboranes

Abstract

Abstract Sterically hindered, in situ generated 1,3,4‐substituted 1,2,3‐triazol‐5‐ylidene mesoionic carbenes (MICs) were employed to stabilize a number of aryl‐ and heteroaryldihaloboranes, as well as the first MIC‐supported diborane. Reduction of borane adducts of the 1‐(2,6‐diisopropylphenyl)‐3‐methyl‐4‐ tert ‐butyl‐1,2,3‐triazol‐5‐ylidene ligand with KC 8 in non‐coordinating solvents led to intramolecular C−H‐ and, C−C‐activation at an isopropyl residue of the supporting ligand. DFT calculations showed that each of these activation reactions proceeds via a different isomer of a borylene intermediate.