Chemical Identity and Structural Features

6-Chloro-1H-indazole-5-carboxylic acid methyl ester (SKU: C173726) belongs to the indazole family of nitrogen-containing bicyclic heterocycles, consisting of a benzene ring fused to a pyrazole ring. The compound carries three key structural features: (1) a chlorine atom at the C-6 position, which serves as a handle for cross-coupling reactions such as Suzuki–Miyaura and Buchwald–Hartwig amination; (2) a methyl ester group at the C-5 position, enabling further functional-group interconversions including hydrolysis to the free carboxylic acid, reduction to the alcohol, or aminolysis to amide derivatives; and (3) a free N-H at the N-1 position, which can be selectively protected or alkylated to modulate pharmacokinetic properties. This combination of reactive sites makes the compound a highly versatile intermediate for the construction of complex drug-like molecules.

The indazole core is bioisosteric with indole and benzimidazole, and appears frequently in approved pharmaceuticals and clinical candidates. Its planar aromatic character facilitates pi-stacking interactions with biological targets such as kinases, GPCRs, and nuclear receptors.

Recommended Handling and Storage Conditions

Personal Protective Equipment (PPE): Handle 6-Chloro-1H-indazole-5-carboxylic acid methyl ester wearing appropriate laboratory gloves (nitrile recommended), safety glasses or goggles, and a laboratory coat. Work in a well-ventilated fume hood to avoid inhalation of dust or aerosols.

Storage: Store the compound in a tightly sealed container in a cool, dry, and well-ventilated area, away from direct light and incompatible materials such as strong oxidizing agents and strong bases. Refrigerated storage (2–8 °C) is generally recommended for long-term stability of methyl ester-containing indazole derivatives; consult the product-specific Certificate of Analysis (CoA) for confirmed conditions. Keep the container sealed when not in use to prevent moisture uptake and N-H tautomerism complications.

Handling Precautions: As with all fine-chemical reagents, minimize exposure time, avoid generating dust, and wash hands thoroughly after handling. Dispose of waste in accordance with local institutional and regulatory guidelines for halogenated organic compounds.

Synthetic Applications and Reaction Protocols

The dual electrophilic handles present in 6-Chloro-1H-indazole-5-carboxylic acid methyl ester make it amenable to a range of synthetic transformations:

• Palladium-Catalyzed Cross-Coupling at C-6: The aryl chloride can participate in Suzuki–Miyaura (boronic acid partners), Negishi (organozinc), or Buchwald–Hartwig (amine partners) couplings under standard Pd(0)/Pd(II) catalytic conditions. Typical ligands include SPhos, XPhos, or BINAP depending on the coupling partner. The reaction is generally run under inert atmosphere (N₂ or Ar) in solvents such as dioxane, toluene, or DMF with Cs₂CO₃ or K₃PO₄ as base.
• Ester Hydrolysis (C-5 Methyl Ester): Saponification with LiOH or NaOH in aqueous THF/MeOH at room temperature or mild heating converts the methyl ester to the corresponding carboxylic acid, which can be used directly in amide-bond-forming reactions (HATU, EDC/HOBt coupling conditions).
• N-1 Alkylation: The indazole N-H can be selectively alkylated using alkyl halides and a mild base (K₂CO₃) in DMF, or protected as the SEM, Boc, or Bn derivative, enabling orthogonal elaboration of the molecule.
• Sequential Functionalization: A common strategy is to first perform N-1 protection, then C-6 cross-coupling, followed by ester hydrolysis and amide coupling, building complexity in a controlled, stepwise fashion.

All reactions should be optimized at small scale (0.1–0.5 mmol) before scale-up. Reaction progress can be conveniently monitored by TLC (UV active, 254 nm) or UPLC-MS.

Quality, Purity, and Analytical Characterization

Aladdin Scientific supplies 6-Chloro-1H-indazole-5-carboxylic acid methyl ester (C173726) with a Certificate of Analysis (CoA) documenting purity, appearance, and analytical data. Researchers should verify the following upon receipt:

• Purity Assessment: High-performance liquid chromatography (HPLC) or UPLC is the standard method for purity determination. A purity of ≥95% (area%) is typical for research-grade indazole intermediates. Refer to the CoA for the lot-specific purity value.
• Identity Confirmation: ¹H NMR spectroscopy is recommended for identity confirmation. Key expected signals include the indazole N-H (broad, 11–13 ppm), aromatic protons in the 7–8.5 ppm region, and the methyl ester singlet near 3.9–4.0 ppm. ¹³C NMR and high-resolution mass spectrometry (HRMS) provide complementary confirmation.
• Appearance: The compound is expected to be a solid (powder or crystalline); color may range from white to off-white or pale yellow. Significant discoloration may indicate degradation.
• Moisture Sensitivity: Although not classified as highly moisture-sensitive, prolonged exposure to humid conditions may promote hydrolysis of the methyl ester over extended periods. Store desiccated if long-term storage is required.

For regulatory or GMP-adjacent applications, request a full CoA and additional documentation from Aladdin Scientific customer service.

Ordering and Customer Support

6-Chloro-1H-indazole-5-carboxylic acid methyl ester is available from Aladdin Scientific under SKU C173726. To place an order or request a quotation:

• Visit the Aladdin Scientific website and search by SKU C173726 or product name.
• For bulk quantities, custom packaging, or priority shipping requirements, contact our sales team directly through the website inquiry form or by email.
• A Certificate of Analysis (CoA) can be downloaded from the product page by entering the lot number, or requested from customer service.
• Aladdin Scientific offers reward points and promotional pricing for qualifying orders — refer to current promotions on the website for details.
• For returns, replacements, or quality complaints, please review the Returns and Refunds policy on the Aladdin Scientific website and contact customer service with order details and relevant documentation.

Our technical support team is available to assist with application questions, structure confirmation, and selection of related building blocks for your research program.