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Organic Letters· 2026Q1

Construction of Tetrahydropyridobenzimidazoles via Ni–Al Bimetal-Catalyzed Tandem C(sp2)/C(sp3)–H Annulation

Shao-long Qi, Weiwei Xu, Mengchun Ye

Short summary

A Ni–Al bimetallic catalyst enables a tandem C(sp2)–H/C(sp3)–H annulation of N-alkyl benzimidazoles with alkynes, yielding tetrahydropyridobenzimidazoles in 40-98% yields.

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Key points

  • A Ni–Al bimetallic catalyst was developed for tandem C(sp2)–H/C(sp3)–H annulation.
  • The reaction couples N-alkyl benzimidazoles with alkynes.
  • This strategy allows access to tetrahydropyridobenzimidazoles, overcoming limitations of previous methods.
  • Yields ranged from 40% to 98% for the synthesized compounds.

AI-generated from the title and abstract; the full text is not read.

Abstract

Abstract Tetrahydropyridobenzimidazoles are privileged heterocyclic motifs prevalent in bioactive molecules. While transition-metal-catalyzed C–H annulation of benzimidazoles has emerged as a highly atom-economical approach, current strategies are largely limited to single C–H and dual C(sp2)–H annulation; these systems afford (hydro)pyridobenzimidazoles but cannot access tetrahydropyrido-fused analogues, because they are hampered by the low reactivity of aliphatic C(sp3)–H bonds. Herein, we report a tandem C(sp2)–H/C(sp3)–H annulation of N-alkyl benzimidazoles with alkynes enabled by a phosphine oxide-ligating Ni–Al bimetallic catalyst, furnishing various tetrahydropyridobenzimidazoles in 40–98% yields from readily available starting materials.

The authors' abstract, as published at the source. Organic Letters, 2026 · DOI ↗

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Field: Organic Chemistry

Organic ChemistryChemistry