3-(Benzyloxy)-5-Bromophenylboronic Acid: Key FAQs

3-(Benzyloxy)-5-bromophenylboronic acid is a bifunctional arylboronic acid building block bearing both a boronic acid group for palladium-catalyzed cross-coupling reactions and a benzyloxy-protected phenol alongside a bromine handle for further diversification.

CAS Number

Not specified in source material — see product datasheet

SKU / Catalog Number

B180663

Molecular Formula

C13H12BBrO3 (boronic acid form)

Functional Groups

Boronic acid (–B(OH)2), aryl bromide (C–Br), benzyloxy ether (–OCH2Ph)

Primary Application

Suzuki–Miyaura cross-coupling; synthesis of polysubstituted biaryl scaffolds

Recommended Storage

Cool, dry conditions; protect from moisture; store under inert atmosphere when possible

What Is 3-(Benzyloxy)-5-Bromophenylboronic Acid and Why Is It Useful?

3-(Benzyloxy)-5-bromophenylboronic acid (Aladdin SKU B180663) is an arylboronic acid in which the phenyl ring carries three substituents at defined positions: a boronic acid group (–B(OH)₂) at C-1, a benzyloxy group (–OCH₂Ph) at C-3, and a bromine atom at C-5. This combination makes it a bifunctional synthetic building block that can participate in two conceptually orthogonal transformations in the same molecule.

The boronic acid moiety is the primary handle for Suzuki–Miyaura palladium-catalyzed cross-coupling, one of the most widely used C–C bond-forming reactions in medicinal chemistry, materials science, and natural-product synthesis. The aryl bromide at C-5 is a second, independent electrophilic site that can undergo its own palladium- or nickel-catalyzed coupling, nucleophilic aromatic substitution, or metal–halogen exchange, enabling sequential functionalization strategies. The benzyloxy group serves as a mild, orthogonally removable protecting group for a phenol: it can be cleanly cleaved by hydrogenolysis (H₂, Pd/C) without disturbing most other functional groups, unmasking a free –OH for further elaboration.

This combination of reactivity makes the compound particularly attractive for building complex, drug-like polyaromatic frameworks in a stepwise manner.

How Should This Compound Be Stored and Handled?

Moisture sensitivity: Boronic acids, including this compound, are susceptible to protodeboronation and anhydride (boroxine) formation in the presence of water. Store the reagent in a tightly sealed vial in a cool, dry location. If your laboratory experiences high humidity, consider storing the sealed vial inside a desiccator containing silica gel or molecular sieves.

Inert atmosphere: While arylboronic acids are generally less air-sensitive than organolithium or Grignard reagents, prolonged exposure to moist air can lead to slow oxidation or hydrolysis of the boronic acid functionality. For long-term storage or after partial use, re-seal under nitrogen or argon.

Temperature: Room-temperature storage is acceptable for short periods; for extended storage, a refrigerator (2–8 °C) is preferable. Always allow cold vials to equilibrate to room temperature before opening to prevent condensation on the solid.

Handling precautions: As with all organoboron and organobromine compounds, follow standard laboratory chemical hygiene practices. Consult the Safety Data Sheet (SDS) provided by Aladdin Scientific before use. Weigh in a well-ventilated fume hood and avoid inhalation of fine powder.

How Is This Boronic Acid Used in Suzuki–Miyaura Cross-Coupling?

In a typical Suzuki–Miyaura reaction, 3-(Benzyloxy)-5-bromophenylboronic acid acts as the nucleophilic boronic acid partner that couples with an aryl or vinyl halide (or pseudohalide such as a triflate) in the presence of a palladium catalyst and an inorganic base. Standard conditions include:

• Catalyst: Pd(PPh₃)₄, Pd(dppf)Cl₂, or Pd(OAc)₂ with a phosphine ligand (1–5 mol%)
• Base: K₂CO₃, Cs₂CO₃, or Na₂CO₃ (2–3 equivalents)
• Solvent: DMF, THF, dioxane, or toluene/water mixtures
• Temperature: 60–100 °C, 1–18 h

The boronic acid group reacts selectively under these conditions while the aryl bromide at C-5 remains largely intact if no additional electrophile is introduced, enabling chemoselective coupling. The boronic acid is generally more reactive than the aryl C–Br bond toward palladium oxidative addition under mild conditions, but this chemoselectivity should be confirmed experimentally for each specific substrate pair.

After Suzuki coupling, the C-5 aryl bromide can be engaged in a second cross-coupling step, and the benzyloxy group can subsequently be removed by hydrogenolysis to reveal the free phenol — enabling a three-step diversification strategy from a single building block.

Purity, Quality, and Analytical Verification

Aladdin Scientific provides 3-(Benzyloxy)-5-bromophenylboronic acid (B180663) with a specification sheet detailing purity by HPLC or GC and identity by NMR and/or mass spectrometry. Researchers should request or download the Certificate of Analysis (CoA) for the specific lot number received.

Key analytical checkpoints for end-users:

• ¹H NMR: three aromatic protons in the 7.3–7.9 ppm region consistent with a 1,3,5-trisubstituted ring; benzyl –OCH₂– singlet near 5.1 ppm; –B(OH)₂ protons often broad or absent in common deuterated solvents.
• Mass spectrometry (ESI or EI): confirm molecular ion consistent with C₁₃H₁₂BBrO₃; note the characteristic isotope pattern for bromine (approx. 1:1 ratio of M and M+2).
• TLC: useful for rapid identity confirmation; run against an authentic standard if available.
• Boronic acid functionality can be confirmed by reaction with a diol (e.g., pinacol) to form the pinacol boronate ester, which is more stable and shows a distinct ¹¹B NMR signal.

If the compound has been stored for an extended period, re-verify purity before use in sensitive applications, as partial conversion to boroxine or oxidative byproducts may occur.

Ordering, Availability, and Regulatory Considerations

How to order: 3-(Benzyloxy)-5-bromophenylboronic acid is available from Aladdin Scientific under catalog number B180663. Orders can be placed through the Aladdin Scientific website, by contacting your regional sales representative, or via approved procurement portals used by your institution.

Packaging and quantities: Please refer to the current product listing on the Aladdin Scientific website for available pack sizes and pricing. Bulk quantities may be available upon request.

Shipping: The compound is shipped as a solid at ambient temperature in standard packaging. Consult the SDS for UN number, hazard class, and any transport-specific requirements applicable to your region.

Regulatory status: This compound is intended for research use only (RUO) and is not approved for use in diagnostic, therapeutic, or food applications. Purchasers are responsible for compliance with all applicable local, national, and international regulations governing the purchase, transport, storage, and disposal of chemical reagents.

Returns and technical support: If the product does not meet the stated specifications, contact Aladdin Scientific customer service with your lot number and CoA. Returns and refunds are handled per Aladdin Scientific's standard returns policy.

Frequently asked questions

Can the boronic acid and aryl bromide groups be reacted independently in a one-pot or sequential synthesis?

Yes. Under typical Suzuki–Miyaura conditions optimized for boronic acids (mild base, lower temperature, Pd catalyst), the C–B bond reacts preferentially with an added aryl halide electrophile while the C–Br bond is largely preserved. In a subsequent step, the intact aryl bromide can be engaged in a second cross-coupling or other transformation. However, chemoselectivity depends on the specific substrates, catalyst, and conditions, so preliminary optimization experiments are recommended.

How do I remove the benzyloxy protecting group after coupling reactions?

The benzyloxy (–OCH2Ph) group is most commonly removed by catalytic hydrogenolysis using H2 gas (1 atm) and palladium on carbon (Pd/C, 10 wt%) in a protic solvent such as ethanol or methanol at room temperature. This cleanly converts the benzyl ether to the free phenol and toluene. Note that aryl bromides may also be partially hydrodehalogenated under these conditions; if the C–Br bond needs to be retained, alternative deprotection methods (e.g., Lewis acid-mediated or transfer hydrogenolysis) should be explored.

What is the shelf life of 3-(Benzyloxy)-5-bromophenylboronic acid and how can I tell if it has degraded?

A specific shelf life is not stated in the available product information; consult the CoA for the recommended use-by date. Signs of degradation include discoloration of the solid, clumping due to moisture uptake, or the appearance of new spots by TLC. For critical applications, verify purity by HPLC or NMR before use. Proper storage (sealed, cool, dry, inert atmosphere) significantly extends usable lifetime.

Is this compound compatible with microwave-assisted Suzuki coupling protocols?

Arylboronic acids are generally well-suited to microwave-assisted Suzuki coupling, which can reduce reaction times from hours to minutes. Standard microwave Suzuki conditions (sealed vial, aqueous base, Pd catalyst, 100–150 °C, 10–30 min) should be compatible with this compound. Optimize power and temperature carefully to avoid decomposition of the boronic acid or the benzyloxy protecting group at elevated temperatures.

Where can I find the Safety Data Sheet (SDS) for B180663?

The Safety Data Sheet for 3-(Benzyloxy)-5-bromophenylboronic acid (B180663) is available for download on the Aladdin Scientific product page for this SKU. If you cannot locate it, contact Aladdin Scientific customer service directly. Always consult the SDS before handling any chemical reagent for the first time.

References

1. Miyaura, N.; Suzuki, A. Palladium-Catalyzed Cross-Coupling Reactions of Organoboron Compounds. Chemical Reviews 1995, 95 (7), 2457–2483. doi:10.1021/cr00039a007
2. Hall, D. G. (Ed.) Boronic Acids: Preparation and Applications in Organic Synthesis, Medicine and Materials, 2nd ed.; Wiley-VCH: Weinheim, 2011.
3. Aladdin Scientific. Product Datasheet and Certificate of Analysis: 3-(Benzyloxy)-5-bromophenylboronic acid, SKU B180663.

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.