Compound Overview and Structural Features

Ethyl 5-amino-1-(2-bromophenyl)-1H-pyrazole-4-carboxylate (Aladdin SKU: E731957) is an N-aryl aminopyrazole carboxylate ester belonging to the broad class of pyrazole heterocycles. The molecule contains three synthetically versatile functional groups arranged on the five-membered pyrazole ring: (1) a primary amine at the 5-position capable of acylation, sulfonylation, reductive amination, and cyclization reactions; (2) an ethyl ester at the 4-position amenable to hydrolysis, transesterification, and Knoevenagel-type condensations; and (3) an ortho-bromophenyl group at N-1 that serves as a handle for palladium-catalyzed cross-coupling reactions, including Suzuki–Miyaura, Buchwald–Hartwig, and intramolecular C–N or C–C bond-forming cyclizations.

The 2-bromophenyl substitution at N-1 is particularly noteworthy: the ortho geometry places the bromine in proximity to the pyrazole ring, enabling intramolecular cyclization strategies to construct fused polycyclic systems such as pyrazolo[1,5-a]pyridines or related scaffolds. This combination of features makes the compound a privileged building block in drug discovery and heterocyclic synthesis programs.

Safety and Handling Precautions

Before working with Ethyl 5-amino-1-(2-bromophenyl)-1H-pyrazole-4-carboxylate, consult the current Safety Data Sheet (SDS) provided by Aladdin Scientific. As with most fine-chemical intermediates bearing an aromatic amine and an aryl halide, the following general precautions apply:

• Personal Protective Equipment (PPE): Wear nitrile gloves, a laboratory coat, and safety goggles at all times. A dust mask or half-face respirator is recommended when handling the powder form to avoid inhalation of fine particulates.
• Ventilation: All weighing, dissolution, and reaction steps should be performed in a well-ventilated fume hood.
• Skin and Eye Contact: In the event of skin contact, wash immediately with soap and copious water for at least 15 minutes. For eye contact, rinse with water for at least 15 minutes and seek medical attention.
• Waste Disposal: Dispose of all waste materials, including contaminated solvent and glassware rinses, in accordance with local institutional and governmental regulations for chemical waste.

This compound is not classified as a bulk industrial chemical; it is intended for laboratory research use only and should not be used for any other purpose.

Dissolution, Solubility, and Stock Solution Preparation

Ethyl 5-amino-1-(2-bromophenyl)-1H-pyrazole-4-carboxylate is an organic solid that is expected to show good solubility in common polar aprotic organic solvents based on its structural features. Recommended solvents and guidelines are provided below:

• Dimethyl sulfoxide (DMSO): Generally the first-choice solvent for preparing concentrated stock solutions intended for biological screening assays. Prepare a 10–50 mM stock solution and store at –20 °C in tightly capped vials under an inert atmosphere (argon or nitrogen) to prevent moisture uptake and oxidation.
• Dimethylformamide (DMF) or N-methyl-2-pyrrolidone (NMP): Suitable for synthetic applications requiring higher-temperature reaction conditions.
• Ethanol or methanol: Protic solvents may be used for recrystallization or when DMSO is incompatible with a downstream assay.
• Dichloromethane (DCM) or ethyl acetate: Suitable for chromatographic workup and routine manipulations.

Preparation procedure: Tare a clean, dry, tightly fitting glass vial. Transfer the desired mass of compound using a microspatula. Add the appropriate volume of solvent and vortex or sonicate briefly (30–60 seconds) until complete dissolution is achieved. Do not heat above 50 °C to avoid ester hydrolysis or decomposition of the amino group. Verify complete dissolution visually before use. Prepare fresh aliquots where possible; avoid repeated freeze–thaw cycles.

Note: Precise solubility values in specific solvents are not available in the current source material and should be determined experimentally or confirmed with Aladdin Scientific technical support.

Typical Synthetic Applications and Reaction Protocol

Owing to its trifunctional character, Ethyl 5-amino-1-(2-bromophenyl)-1H-pyrazole-4-carboxylate finds use in several categories of synthetic transformations:

1. Intramolecular Palladium-Catalyzed Cyclization

The ortho-bromophenyl group and the proximal amino group at C-5 can be exploited for intramolecular Buchwald–Hartwig-type amination or C–H functionalization to afford fused bicyclic or tricyclic pyrazolo-heterocycles. A general procedure would involve:

• Pd catalyst (e.g., Pd₂(dba)₃ or Pd(OAc)₂), 1–5 mol%
• Phosphine ligand (e.g., BINAP, XPhos, or dppf), 2–10 mol%
• Base (e.g., Cs₂CO₃ or K₃PO₄), 2–3 equiv
• Solvent: toluene, dioxane, or DMF; 80–110 °C; 12–24 h under inert atmosphere

2. Suzuki–Miyaura Cross-Coupling at the Aryl Bromide

The aryl bromide can be coupled with arylboronic acids or boronate esters to diversify the biaryl substituent at N-1:

• Pd(PPh₃)₄ or Pd(dppf)Cl₂, 2–5 mol%
• Arylboronic acid, 1.2–1.5 equiv
• K₂CO₃ or Na₂CO₃, 2–3 equiv
• Solvent: EtOH/water or DMF/water; 80–90 °C; 6–12 h

3. Acylation or Cyclization via the C-5 Amino Group

The primary amine can be acylated with acid chlorides or anhydrides to give amide derivatives, or reacted with isocyanates to afford urea products. Condensation with 1,3-dicarbonyl or orthoacid esters can afford aminoheterocycle extensions useful in kinase inhibitor scaffolds.

Caution: Reaction conditions listed above are general guidance derived from standard heterocyclic chemistry practice. Researchers should optimize conditions experimentally for their specific synthetic targets. Specific yields and conditions from published literature should be identified by the research team and cited accordingly.

Storage, Stability, and Quality Control

Storage conditions: Store Ethyl 5-amino-1-(2-bromophenyl)-1H-pyrazole-4-carboxylate in a tightly sealed container in a cool, dry, and dark environment. A storage temperature of 2–8 °C or ambient temperature (as specified on the product label) is generally appropriate for stable solid organic intermediates. Keep away from moisture, strong oxidizers, strong acids, and strong bases.

Stability considerations: The ethyl ester functional group may undergo slow hydrolysis under prolonged exposure to moisture or aqueous acidic/basic conditions. The primary amine may be susceptible to oxidation on extended storage under air. To maximize shelf life:

• Backfill the container with argon or nitrogen after each use.
• Use desiccant-packed storage or place in a desiccator.
• Avoid repeated opening of the original container; prepare aliquots in smaller vials.

Quality control: Aladdin Scientific performs standard characterization on research-grade reagents. Upon receipt, researchers may verify compound identity and purity using:

• ¹H and ¹³C NMR spectroscopy
• High-resolution mass spectrometry (HRMS)
• HPLC purity determination (reverse-phase C18 column)
• Melting point determination and comparison with literature values (where available)

Specific purity specifications and Certificate of Analysis (CoA) details should be obtained directly from Aladdin Scientific at the time of purchase.