Compound Overview and Properties

6-(2-Furyl)-1-isopropyl-1H-pyrazolo[3,4-b]pyridine-4-carboxylic acid (Aladdin SKU F187945) is a fused bicyclic heterocycle combining a pyrazole ring and a pyridine ring. The compound bears three key functional motifs: an N-isopropyl substituent on the pyrazole nitrogen, a 2-furyl group at the 6-position providing an additional aromatic heteroaromatic handle, and a free carboxylic acid at the 4-position that is the primary site for synthetic elaboration.

The pyrazolo[3,4-b]pyridine core is a privileged scaffold in drug discovery, appearing in kinase inhibitors and other bioactive molecules. The free carboxylic acid makes this compound an ideal building block for the introduction of amide, ester, or other acyl-derived bonds.

Appearance: Typically a solid powder (exact color may vary; verify with certificate of analysis).

Molecular formula: C₁₄H₁₃N₃O₃ (verify against CoA).

Safety and Handling

Handle 6-(2-Furyl)-1-isopropyl-1H-pyrazolo[3,4-b]pyridine-4-carboxylic acid using standard laboratory safety precautions appropriate for research-grade organic compounds:

• Personal Protective Equipment (PPE): Wear nitrile gloves, a laboratory coat, and safety glasses at all times during handling.
• Ventilation: Work in a well-ventilated fume hood, especially when weighing or preparing solutions, to minimize inhalation of dust.
• Skin and Eye Contact: Avoid direct contact. In case of skin contact, wash the affected area with soap and water for at least 15 minutes. In case of eye contact, flush with copious water and seek medical attention.
• Storage: Store the compound in a tightly sealed container in a cool, dry, dark location. Avoid exposure to moisture and strong oxidizing agents.
• Disposal: Dispose of waste material in accordance with institutional and local regulatory guidelines for organic chemical waste.

Note: A detailed Safety Data Sheet (SDS) should be consulted before first use. Contact Aladdin Scientific for the current SDS for SKU F187945.

Solubility and Solution Preparation Protocol

Proper dissolution is critical for reproducible experimental results. Follow the steps below to prepare stock solutions of 6-(2-Furyl)-1-isopropyl-1H-pyrazolo[3,4-b]pyridine-4-carboxylic acid:

1. Equilibrate to room temperature: Allow the sealed vial to warm to room temperature before opening to prevent moisture condensation on the compound.
2. Select an appropriate solvent: DMSO and DMF are the recommended primary solvents due to the compound's good solubility in polar aprotic solvents. Aqueous solubility is low at neutral pH but increases significantly under basic conditions (e.g., dilute NaOH or aqueous NaHCO₃).
3. Prepare a stock solution: Weigh the required amount of compound accurately using an analytical balance. Dissolve in DMSO to prepare a concentrated stock (e.g., 10–100 mM). Vortex or sonicate gently until fully dissolved.
4. Dilution for assays: Dilute the DMSO stock into the aqueous assay buffer immediately before use. Ensure the final DMSO concentration is compatible with your assay system (typically ≤1% v/v for biological assays).
5. Verification: Confirm complete dissolution visually and, if required, by UV-Vis spectroscopy.
6. Storage of solutions: Store prepared stock solutions at −20 °C under inert atmosphere (e.g., argon) and protect from light. Avoid repeated freeze-thaw cycles.

Note: Actual solubility values have not been independently verified by Aladdin Scientific for this lot; consult the CoA and perform solubility testing as appropriate for your application.

Amide Coupling Protocol Using the Carboxylic Acid

The free carboxylic acid group at the 4-position is ideally suited for standard amide bond-forming reactions. The following general protocol uses HATU/DIPEA as the coupling system, which is compatible with heteroaromatic carboxylic acids:

Materials Required

• 6-(2-Furyl)-1-isopropyl-1H-pyrazolo[3,4-b]pyridine-4-carboxylic acid (F187945), 1.0 equiv.
• Amine coupling partner, 1.0–1.2 equiv.
• HATU (O-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate), 1.1–1.2 equiv.
• DIPEA (N,N-diisopropylethylamine) or Et₃N, 2.0–3.0 equiv.
• Anhydrous DMF or CH₂Cl₂ (solvent)
• Inert atmosphere (N₂ or Ar)

Procedure

1. Dissolve the carboxylic acid (1.0 equiv.) in anhydrous DMF (0.1–0.5 M) under inert atmosphere.
2. Add HATU (1.1–1.2 equiv.) and DIPEA (2.0–3.0 equiv.) and stir for 5–10 minutes at room temperature to pre-activate the acid.
3. Add the amine coupling partner (1.0–1.2 equiv.) and stir the reaction mixture at room temperature for 1–16 hours, monitoring by TLC or LC-MS.
4. Upon completion, dilute with ethyl acetate and wash sequentially with saturated aqueous NH₄Cl, saturated NaHCO₃, and brine.
5. Dry the organic layer over anhydrous Na₂SO₄, filter, and concentrate under reduced pressure.
6. Purify the crude amide product by column chromatography (silica gel) or preparative HPLC as required.

Optimization note: Reaction time, base equivalents, and temperature may need to be adjusted depending on the nucleophilicity of the amine coupling partner. Monitor reaction progress by LC-MS.

Analytical Characterization and Quality Control

To confirm compound identity and purity before use in experiments, the following analytical methods are recommended:

• HPLC Purity: Analyze the compound by reverse-phase HPLC (C18 column, acetonitrile/water gradient with 0.1% TFA or formic acid modifier) to determine purity. Accept lots with ≥95% purity for synthetic applications (verify purity specification on CoA for SKU F187945).
• LC-MS: Confirm molecular weight by electrospray ionization mass spectrometry (ESI-MS). The [M+H]⁺ ion should correspond to the theoretical molecular weight of the compound (verify exact MW against CoA).
• NMR Spectroscopy:
  • ¹H NMR: Confirm the characteristic signals for the isopropyl septet and doublets, the furyl aromatic protons, and the pyrazolopyridine ring protons.
  • ¹³C NMR: Verify the carboxylic acid carbonyl carbon and heteroaromatic carbons.
• Melting Point: Determine the melting point and compare to reference values when available.
• Karl Fischer Titration: If moisture content is critical for your application, perform Karl Fischer analysis before use.

Always retain the Certificate of Analysis (CoA) provided by Aladdin Scientific and cross-reference all analytical data against the stated specifications for lot F187945.