Ru <sup>II</sup> -phosphine catalysed direct synthesis of benzimidazoles <i>via</i> acceptorless dehydrogenative coupling of alcohols with aromatic diamines
We report the synthesis and characterization of Ru<sup>II</sup> complexes containing amide-based phosphine ligands [<i>o</i>-Ph<sub>2</sub>P(C<sub>6</sub>H<sub>4</sub>)C(O)N(H)C<sub>6</sub>H<sub>4</sub>(<i>o</i>-OR)] (L1 R = Me; L2 R = Et; L3 R = <sup>i</sup>Pr). Reaction of ligands L1-L3 with [Ru(<i>p</i>-cymene)Cl<sub>2</sub>]<sub>2</sub> afforded the corresponding complexes [(RuCl)(η<sup>6</sup>-<i>p</i>-cymene)(L1-3)-κ<sup>2</sup>-P,O][Cl] (1 R = Me, 2 R = Et, and 3 R = <sup>i</sup>Pr). These complexes exhibit excellent catalytic activity in the selective synthesis of 2-substituted and 1,2-disubstituted benzimidazoles, with product selectivity governed by alcohol concentration. Control experiments revealed the operation of both acceptorless dehydrogenative and oxidative coupling pathways. Furthermore, the catalytic protocol was successfully extended to a broad range of substrates, delivering diverse benzimidazole derivatives in moderate to excellent yields.
Authors
- Maravanji S. Balakrishna (ORCID: https://orcid.org/0000-0003-3736-6148)
- Ankit Kumar Pandey (ORCID: https://orcid.org/0000-0002-3388-7416)
Institutions
- Indian Institute of Technology Bombay (IN)
Publication Details
- Journal
- Organic & Biomolecular Chemistry
- Published
- 2025-01-01
- DOI
- https://doi.org/10.1039/d5ob01280e
- Citations
- 1
- Primary Topic
- Asymmetric Hydrogenation and Catalysis
- Type
- article
- Field-Weighted Citation Impact
- 0.54