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Updated: Jun 19, 2026

Synthesis of a Borylated Ibuprofen Derivative Through Suzuki Cross-Coupling and Alkene Boracarboxylation Reactions
Published on: November 30, 2022
Superelectrophilic intermediates in nitrogen-directed aromatic borylation
Timothy S De Vries1, Aleksandrs Prokofjevs, Jeremy N Harvey
1Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA.
This study introduces novel borylation reactions forming cyclic borenium ions from hydrogen-bridged boron cations. These reactions utilize hydride abstraction and demonstrate unique cyclization pathways, confirmed by spectroscopy and computational analysis.
Area of Science:
- Organometallic Chemistry
- Organic Synthesis
- Computational Chemistry
Background:
- Borylation reactions are crucial in organic synthesis.
- Generation and reactivity of borenium ions are of significant interest.
- Understanding reaction mechanisms involving boron cations is essential for developing new synthetic methodologies.
Purpose of the Study:
- To describe the first examples of borylation via hydrogen-bridged boron cations.
- To investigate the formation of cyclic borenium ions and related derivatives.
- To elucidate the reaction mechanism using experimental and computational approaches.
Main Methods:
- Hydride abstraction from N,N-dimethylamine boranes using Ph(3)C(+) (C(6)F(5))(4)B(-) (TrTPFPB).
- Reductive quenching experiments, (11)B and (1)H NMR spectroscopy for product characterization.
- Density functional theory (DFT) calculations (B3LYP/6-31G*) to evaluate cationic intermediates and transition states.
Main Results:
- Successful generation of hydrogen-bridged cations and their subsequent internal borylation to cyclic amine borane derivatives.
- Formation of cyclic borenium ions confirmed for specific substrates (Ar = C(6)H(5), n = 1 and Ar = o-C(6)H(4)SiMe(3)).
- Observation of a unique cyclization product with a tert-butyl substituent and a significant kinetic isotope effect (k(H)/k(D) = 2.8) for an ortho-deuterated substrate.
Conclusions:
- The study demonstrates a new route to borylation through hydrogen-bridged boron cations.
- Reaction mechanisms involve C-H insertion or Wheland intermediates, with pathways influenced by substrate substituents.
- Computational and experimental data provide insights into the formation and stability of borenium ions and cyclization products.
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