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Updated: Dec 28, 2025

Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions
Published on: July 30, 2017
Protocol for Visible-Light-Promoted Desulfonylation Reactions Utilizing Catalytic Benzimidazolium Aryloxide Betaines
Eietsu Hasegawa1, Tsukasa Tanaka1, Norihiro Izumiya1
1Department of Chemistry, Faculty of Science, Niigata University, 8050 Ikarashi-2, Nishi-ku, Niigata 950-2181, Japan.
Abstract:
An unprecedented photocatalytic system consisting of benzimidazolium aryloxide betaines (BI+-ArO-) and stoichiometric hydride reducing reagents was developed for carrying out desulfonylation reactions of N-sulfonyl-indoles, -amides, and -amines, and α-sulfonyl ketones. Measurements of absorption spectra and cyclic voltammograms as well as density functional theory (DFT) calculations were carried out to gain mechanistic information. In the catalytic system, visible-light-activated benzimidazoline aryloxides (BIH-ArO-), generated in situ by hydride reduction of the corresponding betaines BI+-ArO-, donate both an electron and a hydrogen atom to the substrates. A modified protocol was also developed so that a catalytic quantity of more easily prepared hydroxyaryl benzimidazolines (BIH-ArOH) is used along with a stoichiometric hydride donor to promote the photochemical desulfonylation reactions.
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