What Is 1-Methyl-4-pyrazole Boronic Acid Pinacol Ester CAS 761446-44-0?

1-Methyl-4-pyrazole boronic acid pinacol ester, identified by CAS No. 761446-44-0, is a heteroaryl boronate ester used primarily as a building block in synthetic chemistry. It combines a 1-methylpyrazole ring with a pinacol-protected boronate group, making it suitable for palladium-catalyzed Suzuki–Miyaura coupling and related carbon–carbon bond-forming reactions. Its commonly reported molecular formula is C₁₀H₁₇BN₂O₂, with a molecular weight of approximately 208.07 g/mol. At Maison Chemical, I recommend evaluating this material through identity, assay, impurity profile, packaging, documentation, and application-specific supply requirements rather than relying on the CAS number alone.

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Direct Definition and Chemical Identity

This compound is a boronic acid pinacol ester, often abbreviated as a Bpin derivative. The pinacol group protects the boronic acid functionality and can improve handling and compatibility during certain synthetic operations. The pyrazole ring provides a nitrogen-containing heteroaromatic structure that may be retained in the final molecule after coupling.

In practical terms, the molecule contains three important structural elements: a methyl-substituted pyrazole core, a boron atom, and a cyclic pinacol ester group. The boronate portion is designed to participate in cross-coupling chemistry, while the pyrazole fragment contributes a functional heteroaryl unit to the target intermediate. The exact commercial description may vary slightly between catalogs, so I advise buyers to confirm the chemical name, CAS number, molecular formula, and structure in the supplier’s specification sheet.

Core Functions and Synthetic Value

Role in Cross-Coupling Chemistry

The primary function of 1-methyl-4-pyrazole boronic acid pinacol ester is to serve as a coupling partner in the formation of aryl–heteroaryl or heteroaryl–heteroaryl bonds. Under a suitable Suzuki–Miyaura reaction system, the boronate group can react with an aryl or heteroaryl halide in the presence of a compatible palladium catalyst and base. The result is the transfer of the pyrazolyl fragment into a more complex molecular framework.

I treat this material as a synthetic intermediate rather than a finished pharmaceutical ingredient. Its value depends on reaction compatibility, purity, moisture control, and the requirements of the downstream route. A successful process may require optimization of catalyst loading, base, solvent, temperature, atmosphere, and reaction time because these variables differ between substrates.

Use as a Heteroaryl Building Block

Pyrazole-containing structures appear in medicinal chemistry, agrochemical research, and specialty chemical development. The 1-methyl substitution changes the electronic and steric character of the pyrazole ring and may be selected to support the design of a particular target structure. However, the presence of a pyrazole boronate ester does not by itself establish a specific biological effect, regulatory status, or therapeutic use.

Application Scenarios

One common application scenario is early-stage pharmaceutical research, where chemists use the compound to introduce a methylpyrazole group into a lead structure. It may also be relevant to process development when a development team needs a defined heteroaryl intermediate for route screening or scale-up evaluation. In each case, the buyer should define the required assay, impurity limits, residual solvent expectations, and documentation before placing an order.

Another scenario is custom synthesis and contract research. A research organization may use this building block to prepare a small library of related compounds, compare substitution patterns, or investigate structure–activity relationships. For larger-scale work, the material must be assessed not only for laboratory reactivity but also for batch-to-batch consistency, packaging suitability, transport conditions, and repeat supply capacity.

Key Properties and Specifications

The following data points are useful for initial identification, but they should be confirmed against the current batch specification or certificate of analysis. Chemical appearance, assay, water content, and impurity limits can vary according to manufacturing route, purification method, and storage history. I recommend using the supplier’s controlled documentation as the final reference for purchasing and quality release.

Many boronate esters are supplied as solid research chemicals, but I do not recommend assuming a specific color, melting range, particle size, or physical form without batch-level confirmation. Buyers should request an analytical package that may include HPLC or GC assay, NMR identity data, water determination, residual solvent information, and relevant impurity results. If the compound is intended for regulated development, the required test methods should be agreed upon before production.

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Handling, Storage, and Process Considerations

I advise handling this material in accordance with the supplier’s safety data sheet and the receiving laboratory’s chemical hygiene procedures. Because boronate esters can be affected by moisture, exposure to humid air should be minimized during sampling, weighing, and repacking unless stability data support a different practice. The container should remain tightly closed, clearly labeled, and stored under the conditions stated in the product documentation.

Buyers should also distinguish between short-term research use and longer-term inventory storage. For a project requiring repeated use, it is sensible to review retest or expiry information, container size, secondary packaging, and the availability of reserve samples. I would not make a universal claim about stability duration because stability depends on formulation, package integrity, temperature, humidity, and analytical acceptance criteria.

How to Select a Suitable Supplier

Confirm Identity and Quality Documentation

The first selection factor is reliable identity confirmation. I recommend checking the CAS number, chemical structure, molecular formula, molecular weight, lot number, and appearance description against the quotation and certificate of analysis. If the product is critical to a route, the buyer may also request representative chromatograms or additional analytical data before approving the source.

Review Purity and Impurity Requirements

Nominal purity alone may not be sufficient for route development or scale-up. A buyer should define whether the project needs a general research grade, a high-assay intermediate, or a customer-specific impurity profile. Particular attention may be needed for unreacted pyrazole derivatives, hydrolyzed boronic acid species, residual solvents, inorganic residues, and moisture, depending on the reaction and downstream control strategy.

Evaluate Supply Practicality

Commercial suitability also includes pack size, minimum order quantity, lead time, shipping method, and repeat-batch availability. These factors should be confirmed through a current quotation rather than assumed from an online listing. For development projects, I recommend asking whether Maison Chemical can support sample evaluation, larger batch planning, document review, and a consistent communication process from laboratory quantity to production demand.

Supplier Support from Maison Chemical

As a chemicals supplier and pharmaceutical intermediates manufacturer, Maison Chemical can support an inquiry by first clarifying the intended application, required quantity, target specification, delivery location, and documentation needs. I can then help organize a product review around identity, assay, packaging, lead time, and commercial conditions. Where a standard specification does not fully match the project, the buyer should describe the critical quality attributes so that feasibility can be assessed before commitment.

For procurement teams, useful inquiry information includes the requested CAS number, estimated annual or project quantity, desired package size, preferred delivery schedule, and whether the material is for research, process development, or commercial manufacturing. Providing these details early can reduce avoidable quotation delays and help align the proposed supply route with the buyer’s quality system. Any certification, testing, or regulatory document should be requested specifically and confirmed as available rather than presumed.

Key Takeaways

• 1-Methyl-4-pyrazole boronic acid pinacol ester is a heteroaryl boronate ester with CAS No. 761446-44-0.
• Its commonly reported formula is C₁₀H₁₇BN₂O₂, and its approximate molecular weight is 208.07 g/mol.
• Its main synthetic role is to introduce a 1-methylpyrazole unit through coupling chemistry.
• Purchasing decisions should include batch-specific assay, impurity, moisture, packaging, and documentation review.
• For scale-up, repeat supply, lead time, and specification control are as important as initial product identity.

Conclusion and Next Steps

In answer to the initial question, 1-Methyl-4-pyrazole boronic acid pinacol ester CAS 761446-44-0 is a protected heteroaryl boronate intermediate used mainly for synthetic coupling and molecular construction. Its reported molecular formula and molecular weight provide a useful starting point, but they do not replace batch-level quality documentation. The most appropriate supplier is one that can clearly confirm identity, quality attributes, packaging, delivery conditions, and ongoing supply capability.

Before purchasing, I recommend sending Maison Chemical your required quantity, target purity, application stage, delivery country, and documentation expectations. We can then review the appropriate specification and provide current commercial information for evaluation. This approach helps research and procurement teams move from simple CAS-number matching to a more reliable, application-focused sourcing decision.

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