Overview and Chemical Properties

3-Iodo-1-methyl-1H-indazole-5-carboxylic acid ethyl ester (SKU I179355) is a difunctionalized indazole derivative combining two orthogonal reactive handles: a carbon–iodine bond at the 3-position and an ethyl ester at the 5-position, with the ring nitrogen (N-1) permanently capped by a methyl group. The indazole core is a bicyclic heteroaromatic system composed of a benzene ring fused to a pyrazole ring, widely encountered in bioactive natural products and pharmaceutical candidates.

The C–I bond at C-3 is highly activated toward oxidative addition by transition metals due to the electron-deficient character of the indazole ring, making this position the preferred site for cross-coupling reactions. The N-1 methyl group eliminates NH tautomerism, providing a chemically defined, stable substrate. The ethyl ester at C-5 offers a handle for further elaboration via hydrolysis, amide coupling, or reduction.

Storage and Handling Guidelines

Storage: Store the compound in a tightly sealed vial under an inert atmosphere (nitrogen or argon) in a cool (2–8 °C recommended), dry, and dark environment. Prolonged exposure to light, moisture, or air may lead to slow oxidative degradation or hydrolysis of the ester functionality.

Personal Protective Equipment (PPE): Wear appropriate laboratory PPE including nitrile gloves, safety glasses, and a lab coat when handling this compound. Although specific acute toxicity data for this compound are not listed in the source material, standard precautions for organoiodine and ester-containing compounds should be observed. Conduct all weighing and transfers in a well-ventilated fume hood.

Waste Disposal: Dispose of all waste in accordance with local institutional and governmental regulations for halogenated organic waste. Do not pour down the drain.

Stability Note: The C–I bond, while reactive under catalytic conditions, is sufficiently stable for routine storage and handling under the recommended conditions. Avoid strong bases that could promote ester hydrolysis or elimination side reactions.

Recommended Synthetic Applications and Protocol

3-Iodo-1-methyl-1H-indazole-5-carboxylic acid ethyl ester is primarily employed as an electrophilic coupling partner in transition-metal-catalyzed reactions. Representative applications include:

• Suzuki–Miyaura Coupling: React with aryl or heteroaryl boronic acids/esters using Pd(PPh₃)₄ or Pd(dppf)Cl₂ as catalyst, K₂CO₃ or Cs₂CO₃ as base, in DMF/water or dioxane/water at 80–100 °C under inert atmosphere. This installs biaryl or heteroaryl groups at C-3 of the indazole.
• Sonogashira Coupling: React with terminal alkynes in the presence of Pd/Cu catalytic system (e.g., PdCl₂(PPh₃)₂/CuI), amine base (Et₃N or diisopropylamine) in DMF or THF at 60–80 °C. This provides C-3 alkynylated indazole derivatives useful in drug discovery scaffolds.
• Ester Hydrolysis / Amide Formation: The C-5 ethyl ester can be saponified with LiOH or NaOH in aqueous THF/MeOH at room temperature to yield the corresponding carboxylic acid, which may then be coupled to amines via standard HATU/DIPEA or EDC/NHS conditions.

General Cross-Coupling Procedure (Suzuki, illustrative):

1. Charge a Schlenk flask or sealed vial with 3-Iodo-1-methyl-1H-indazole-5-carboxylic acid ethyl ester (1.0 equiv), boronic acid partner (1.2–1.5 equiv), Pd catalyst (2–5 mol%), and base (2.0–3.0 equiv).
2. Add degassed solvent (DMF/H₂O, 4:1 v/v) and purge the headspace with nitrogen or argon.
3. Stir at 80–100 °C for 4–16 hours, monitoring by TLC or LC-MS.
4. Cool to room temperature, dilute with ethyl acetate, wash with brine, dry over Na₂SO₄, filter, and concentrate.
5. Purify by column chromatography (silica gel, appropriate eluent) to isolate the 3-aryl-1-methyl-1H-indazole-5-carboxylic acid ethyl ester product.

Note: Reaction conditions should be optimized for each specific coupling partner. The above conditions are illustrative and based on general knowledge of aryl iodide cross-coupling chemistry.

Quality Control and Analytical Characterization

Upon receipt of 3-Iodo-1-methyl-1H-indazole-5-carboxylic acid ethyl ester (SKU I179355), the following analytical methods are recommended for identity and purity verification:

• Thin-Layer Chromatography (TLC): A single spot on TLC (silica, appropriate eluent such as hexane/EtOAc) provides a preliminary purity check. Compare Rf to in-house reference or literature value if available.
• 1H NMR Spectroscopy: Confirm the presence of the N-methyl singlet (~3.9–4.1 ppm), ethyl ester quartet and triplet (~4.4 ppm and ~1.4 ppm respectively), and aromatic/heteroaromatic protons in the 7–8.5 ppm region. No NH signal should be present due to N-methylation.
• 13C NMR and/or DEPT: Verify carbonyl carbon (~165 ppm), aromatic carbons, N-CH₃, and ester ethyl carbons.
• Mass Spectrometry (ESI-MS or APCI-MS): Confirm molecular ion consistent with the molecular formula. The characteristic isotope pattern of iodine (monoisotopic) aids identification.
• HPLC Purity: Reverse-phase HPLC (C18 column, acetonitrile/water gradient) to confirm purity. Typical acceptance criterion for research-grade reagents is ≥95% purity.

Specific spectral data are not provided in the source material and should be verified against the Certificate of Analysis (CoA) supplied with each lot from Aladdin Scientific.

Safety Considerations and Regulatory Notes

While a full Safety Data Sheet (SDS) specific to 3-Iodo-1-methyl-1H-indazole-5-carboxylic acid ethyl ester is not reproduced here, the following precautionary guidance applies based on chemical class:

• Acute Toxicity: Specific LD₅₀ data are not available in the source material. As with all research chemicals, treat as potentially harmful. Avoid inhalation, ingestion, and skin or eye contact.
• Irritancy: Organoiodine compounds and aromatic esters may cause skin and eye irritation. Rinse immediately with copious water upon exposure.
• Environmental Hazard: Halogenated organic compounds may be hazardous to aquatic environments. Dispose in accordance with local regulations for halogenated organic waste.
• Transport and Regulatory Classification: Classification for shipping and regulatory purposes should be confirmed from the product SDS available from Aladdin Scientific prior to transport.

Always consult the current SDS from Aladdin Scientific (available on the product page for SKU I179355) before use, and comply with all applicable local, national, and institutional safety regulations.