Overview and Chemical Properties

2-Bromo-4-fluoro-1-iodobenzene (SKU B152643; CAS 124886-18-6; MW 301.90 g/mol; formula C₆H₃BrFI) is a trihalogenated benzene derivative bearing iodo, bromo, and fluoro substituents at the 1-, 2-, and 4-positions, respectively. The coexistence of three different halogens on a single aromatic ring provides distinct and exploitable reactivity handles for sequential functionalization.

The C–I bond undergoes oxidative addition to Pd(0) and Ni(0) catalysts significantly faster than the C–Br bond, enabling chemoselective mono-coupling at the iodo position without disturbing the bromo substituent under mild conditions. The C–F bond, being the strongest of the three C–halogen bonds, is generally inert under standard cross-coupling conditions and primarily serves an electronic role, withdrawing electron density from the ring and modulating regioselectivity in directed metalation reactions. This combination of orthogonal reactivity makes the compound a valuable building block in multi-step pharmaceutical and materials chemistry synthesis.

Safety and Handling

Personal Protective Equipment (PPE): Always wear chemical-resistant nitrile gloves, a laboratory coat, and safety goggles when handling 2-Bromo-4-fluoro-1-iodobenzene. Work in a well-ventilated fume hood to avoid inhalation of vapors.

Storage: Store the reagent under an inert atmosphere (nitrogen or argon) in a tightly sealed container, refrigerated at 2–8 °C, and protected from light to prevent decomposition and photolytic degradation over time.

Waste Disposal: Dispose of all waste material containing halogenated aromatics in accordance with local, national, and institutional regulations for halogenated organic waste. Do not pour down the drain.

First Aid: In case of skin contact, wash thoroughly with soap and water for at least 15 minutes. In case of eye contact, flush with copious amounts of water and seek medical attention immediately. If inhaled, move to fresh air and consult a physician if symptoms persist.

Note: Consult the current Safety Data Sheet (SDS) for complete hazard information before use.

Step-by-Step Cross-Coupling Protocol (Chemoselective Suzuki–Miyaura at C–I)

The following general protocol describes a chemoselective Suzuki–Miyaura coupling at the C–I position of 2-Bromo-4-fluoro-1-iodobenzene, leaving the C–Br bond intact for subsequent functionalization. Specific reaction conditions (catalyst loading, temperature, solvent ratios) should be optimized for each boronic acid partner.

1. Equipment setup: Oven-dry a round-bottom flask equipped with a magnetic stir bar and a reflux condenser. Fit the system with a three-way stopcock connected to a nitrogen/argon manifold and vacuum line.
2. Reagent preparation: Under inert atmosphere, weigh 2-Bromo-4-fluoro-1-iodobenzene (1.0 equiv, SKU B152643) and the desired arylboronic acid (1.05–1.1 equiv) into the flask. Add the Pd(0) catalyst (e.g., Pd(PPh₃)₄, typically 2–5 mol%) and base (e.g., K₂CO₃ or Cs₂CO₃, 2.0–3.0 equiv).
3. Solvent addition: Add a degassed solvent mixture (e.g., DMF/H₂O or dioxane/H₂O, 4:1 v/v) to give a concentration of approximately 0.1–0.5 M with respect to the aryl iodide. Alternatively, toluene/EtOH/H₂O systems may be used depending on substrate solubility.
4. Degassing: Subject the reaction mixture to three freeze-pump-thaw cycles, or bubble argon through the solution for at least 20 minutes to remove dissolved oxygen, which can deactivate the Pd catalyst.
5. Reaction: Heat the mixture to 80–100 °C (or as dictated by optimization) with stirring under inert atmosphere. Monitor reaction progress by TLC or LC-MS.
6. Workup: Upon completion, cool the reaction to room temperature. Dilute with ethyl acetate and wash sequentially with water and brine. Dry the organic layer over MgSO₄ or Na₂SO₄, filter, and concentrate in vacuo.
7. Purification: Purify the crude product by column chromatography (silica gel, appropriate eluent) or recrystallization. The desired mono-coupled product retains the intact C–Br bond for further derivatization.

Review flag: Specific catalyst, base, solvent, temperature, and time must be validated experimentally. The parameters above are representative starting points only.

Representative Applications

2-Bromo-4-fluoro-1-iodobenzene serves as a versatile building block across several areas of synthetic chemistry:

• Sequential cross-coupling: The C–I bond can be selectively engaged in a first Suzuki–Miyaura, Negishi, or Sonogashira coupling, followed by a second distinct coupling at the C–Br position using different conditions or catalysts, yielding unsymmetrically substituted biaryls or arylalkynes.
• Directed metalation: The fluoro substituent acts as a directed metalation group (DMG) and electron-withdrawing group, enabling regioselective lithiation adjacent to fluorine under controlled low-temperature conditions (e.g., n-BuLi, −78 °C in THF) after appropriate protection or sequential halogen manipulation.
• Pharmaceutical intermediate synthesis: Fluorinated and halogenated arenes are privileged scaffolds in drug discovery. This compound can serve as a key intermediate in constructing fluorinated biaryl pharmacophores found in kinase inhibitors, antifungal agents, and other bioactive molecules.
• Materials chemistry: Sequential functionalization can be used to access conjugated oligomers and polymers for organic electronic applications, where fluorine substitution tunes HOMO/LUMO energy levels and intermolecular packing.

Quality, Purity and Analytical Verification

Before use in sensitive synthetic applications, researchers should verify the identity and purity of 2-Bromo-4-fluoro-1-iodobenzene (SKU B152643) using the following analytical techniques:

• GC or GC-MS: Gas chromatography is the preferred method for purity assessment of liquid or low-melting-point aryl halides. A single major peak with the correct molecular ion (m/z 299/301/303, reflecting the bromine and iodine isotope pattern) confirms identity and purity.
• ¹H NMR: The aromatic proton pattern (three aromatic H expected for a 1,2,4-trisubstituted benzene) provides a rapid identity check. Characteristic coupling constants and chemical shifts distinguish the regioisomer.
• ¹⁹F NMR: A single resonance in the aromatic fluorine region confirms the fluorine substitution pattern.
• HPLC: Reverse-phase HPLC can be used for purity determination when GC is unsuitable.

Aladdin Scientific provides a Certificate of Analysis (CoA) with each batch of B152643. Researchers are encouraged to review the CoA upon receipt and to contact technical support if purity does not meet application requirements.