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1,2-Migration of N-Diarylboryl Imidazol-2-ylidene through Intermolecular Radical Process

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posted on 18.08.2017, 11:51 by Wei-Chun Liu, Yi-Hung Liu, Tien-Sung Lin, Shie-Ming Peng, Ching-Wen Chiu
1,2-Boryl migration of N-boryl N-heterocyclic carbene to 2-boryl imidazole is proposed to proceed through generation and recombination of two radical intermediates, namely, a neutral diarylboron radical and a N-heterocyclic carbene radical. Crossover experiments suggest that these two radical species are stable enough to escape solvent cages and recombine intermolecularly. The presence of radical intermediates is further supported by spin trapping experiments. Besides, the coordination of Li+ cation is found to be critical for the stability of the NHC radical.