3-Bromo-5-ethoxyphenylboronic Acid Pinacol Ester FAQs
3-Bromo-5-ethoxyphenylboronic Acid Pinacol Ester FAQs
3-Bromo-5-ethoxyphenylboronic acid, pinacol ester is a versatile, dual-functional arylboron building block featuring both a reactive C–Br bond and a protected boronate ester on the same aromatic ring, making it highly valuable for sequential or selective cross-coupling strategies in organic synthesis.
- Chemical Name
- 3-Bromo-5-ethoxyphenylboronic acid, pinacol ester
- SKU / Catalog Number
- B179238
- Key Functional Groups
- Aryl C–Br (electrophilic handle), pinacol boronate ester (transmetalation handle), aryl ethoxy substituent
- Primary Application
- Suzuki–Miyaura cross-coupling reactions; sequential bifunctional coupling strategies
- Compound Class
- Halogenated arylboronic acid pinacol ester
- Storage Recommendation
- Store in a cool, dry place under inert atmosphere; protect from moisture
What Is 3-Bromo-5-ethoxyphenylboronic Acid, Pinacol Ester?
3-Bromo-5-ethoxyphenylboronic acid, pinacol ester (Aladdin SKU: B179238) is an arylboron reagent belonging to the class of pinacol boronate esters. Its structure consists of a 1,3,5-trisubstituted benzene ring bearing a bromine atom at the 3-position, an ethoxy (–OEt) group at the 5-position, and a pinacol-protected boronic acid (Bpin) at the 1-position.
The pinacol ester protecting group renders the boronate considerably more stable toward air and moisture compared to the corresponding free boronic acid, while still permitting facile activation for Suzuki–Miyaura transmetalation under standard palladium-catalyzed conditions. The aryl bromide on the same ring provides an independent electrophilic site for additional functionalization, classifying this compound as a bifunctional cross-coupling building block.
Handling, Storage, and Stability
Although pinacol boronate esters are appreciably more hydrolytically stable than free boronic acids, proper handling remains important to maintain reagent integrity and reproducibility.
- Atmosphere: Handle under an inert atmosphere (nitrogen or argon) where possible, particularly once the original packaging is opened.
- Moisture: Avoid prolonged exposure to humid air. Hydrolysis of the pinacol ester can regenerate the free boronic acid, which may subsequently undergo protodeboronation under acidic or basic aqueous conditions.
- Temperature: Store in a cool, dry environment. Refrigerated storage (2–8 °C) is generally recommended for long-term stability; consult the certificate of analysis (CoA) supplied with your specific lot for confirmed storage conditions.
- Container: Re-seal containers tightly after each use and consider storing aliquots under inert gas to minimize headspace exposure.
Always consult the Safety Data Sheet (SDS) provided by Aladdin Scientific before handling, and wear appropriate personal protective equipment (PPE) including gloves, lab coat, and eye protection.
Applications in Cross-Coupling Chemistry
The primary application of 3-Bromo-5-ethoxyphenylboronic acid, pinacol ester is as a nucleophilic coupling partner in palladium-catalyzed Suzuki–Miyaura reactions, where the Bpin group undergoes transmetalation with a palladium(II) intermediate to ultimately form a new C–C bond with an aryl, vinyl, or alkyl electrophile.
Crucially, the intact aryl C–Br bond on this molecule can serve as an additional electrophilic handle in a subsequent or orthogonal coupling step, enabling the construction of complex, multi-aryl architectures from a single building block. Typical synthetic strategies include:
- Sequential Suzuki couplings: First use the Bpin group to couple with one electrophile, then employ the remaining C–Br bond in a second Suzuki or other cross-coupling (e.g., Buchwald–Hartwig amination, Negishi, Heck) reaction.
- Selective mono-coupling: Under carefully controlled conditions, selectively react only the C–Br or only the Bpin group in the presence of the other.
- Fragment assembly: Use as a central arene fragment to build conjugated or medicinal-chemistry-relevant biaryl and terAryl scaffolds.
The ethoxy substituent additionally modulates the electronic character of the ring, providing mild electron-donating character that can influence regioselectivity and reaction rates in downstream transformations.
Purity, Quality, and Regulatory Information
Aladdin Scientific supplies 3-Bromo-5-ethoxyphenylboronic acid, pinacol ester (B179238) as a research-grade reagent. Each lot is accompanied by a Certificate of Analysis (CoA) detailing identity confirmation (e.g., NMR, MS), purity by HPLC or GC, and physical characterization data.
Researchers requiring specific purity thresholds for sensitive applications—such as transition-metal-catalyzed reactions where trace metal impurities can poison catalysts—should consult the CoA or contact Aladdin Scientific technical support to discuss lot-specific data or higher-grade options.
This product is intended for research and development use only and is not approved for use in clinical, diagnostic, or food applications. Users are responsible for compliance with all applicable local regulations governing the purchase, storage, and use of chemical reagents.
Ordering and Technical Support
3-Bromo-5-ethoxyphenylboronic acid, pinacol ester is available from Aladdin Scientific under catalog number B179238. To place an order, request a quotation, or inquire about bulk availability and custom packaging, please visit the Aladdin Scientific website or contact our sales team directly.
For technical questions regarding reaction conditions, compatibility, or analytical data interpretation, our technical support team is available to assist. When contacting support, please have the catalog number (B179238) and your lot number (found on the product label or CoA) available to enable the fastest response.
Frequently asked questions
What makes 3-Bromo-5-ethoxyphenylboronic acid, pinacol ester useful as a bifunctional reagent?
This compound carries both an aryl bromide (C–Br) and a pinacol-protected boronic acid (Bpin) on the same aromatic ring. These two functional groups can participate in cross-coupling reactions independently or sequentially, enabling chemists to build complex biaryl or multi-aryl frameworks from a single, well-defined starting material without requiring additional halogenation or borylation steps.
How should I activate the pinacol boronate ester for a Suzuki–Miyaura coupling reaction?
Pinacol boronate esters typically require no pre-activation; under standard Suzuki–Miyaura conditions—palladium catalyst (e.g., Pd(PPh₃)₄ or Pd(dppf)Cl₂), an aqueous base (e.g., K₂CO₃, Cs₂CO₃, or Na₂CO₃), and a suitable solvent (e.g., DMF, dioxane, THF/water mixtures)—the Bpin group undergoes in situ hydrolysis and transmetalation to deliver the aryl group to the palladium center. Optimization of base strength, temperature, and water content may be needed depending on the specific electrophilic coupling partner used.
Can the aryl bromide in this compound be used in reactions other than Suzuki coupling?
Yes. The aryl C–Br bond is compatible with a broad range of palladium- and nickel-catalyzed cross-coupling methodologies, including Negishi coupling (with organozinc reagents), Heck reactions (with alkenes), Sonogashira coupling (with terminal alkynes), and Buchwald–Hartwig amination (with amines). It can also participate in lithium–halogen exchange under cryogenic conditions if the Bpin group is tolerant of organolithium reagents, although careful optimization is required. This versatility makes B179238 a flexible intermediate for medicinal chemistry and materials science applications.
What are the signs of degradation in a pinacol boronate ester, and how can I verify reagent quality before use?
Degradation of pinacol boronate esters often manifests as hydrolysis to the free boronic acid, which may further undergo protodeboronation to give the deboronated arene. Visually, color changes or the appearance of crystalline deposits inconsistent with the expected product can be indicative. Before use, quality can be confirmed by ¹H NMR (checking for the characteristic pinacol methyl singlet near δ 1.3 ppm and the aryl proton pattern) or by HPLC purity analysis referenced against the CoA provided with each lot. Contact Aladdin Scientific technical support if you observe discrepancies from the CoA data.
Is 3-Bromo-5-ethoxyphenylboronic acid, pinacol ester available in bulk quantities, and what packaging options exist?
Aladdin Scientific offers this compound (B179238) in standard research-scale quantities. For bulk orders or inquiries about custom packaging sizes, please contact the Aladdin Scientific sales team directly through the website or by email. Availability of larger quantities and lead times may vary by region and current inventory; early communication with the procurement team is recommended for time-sensitive projects.
References
- Miyaura, N.; Suzuki, A. Palladium-Catalyzed Cross-Coupling Reactions of Organoboron Compounds. Chemical Reviews 1995, 95 (7), 2457–2483. doi:10.1021/cr00039a007
- Hall, D. G. (Ed.) Boronic Acids: Preparation and Applications in Organic Synthesis, Medicine and Materials, 2nd ed.; Wiley-VCH: Weinheim, 2011.
- Lennox, A. J. J.; Lloyd-Jones, G. C. Selection of boron reagents for Suzuki–Miyaura coupling. Chemical Society Reviews 2014, 43 (1), 412–443. doi:10.1039/c3cs60197h
Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.
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