Compound Overview and Key Properties

Methyl 3-iodo-1H-indole-6-carboxylate (Aladdin SKU: M710164) is a functionalized indole derivative bearing a reactive C-3 carbon–iodine bond and a methyl ester group at the C-6 position of the indole ring. The C–I bond at the electron-rich C-3 position renders this compound an excellent electrophilic partner in transition-metal-catalyzed cross-coupling reactions, including Suzuki–Miyaura, Sonogashira, Negishi, and Heck reactions.

The methyl ester at C-6 provides a handle for further functional group interconversion, such as hydrolysis to the carboxylic acid, reduction to an alcohol, or amide bond formation, making this compound a highly versatile synthetic building block for the preparation of pharmacologically relevant indole-containing molecules.

Researchers should consult the Safety Data Sheet (SDS) supplied by Aladdin Scientific for precise physicochemical data including molecular weight, melting point, and purity specification prior to use.

Safety and Handling Precautions

Before working with Methyl 3-iodo-1H-indole-6-carboxylate, review the current Safety Data Sheet (SDS). As with all fine chemical reagents, treat this compound as potentially irritating to skin, eyes, and the respiratory tract until specific hazard data are confirmed.

• Personal Protective Equipment (PPE): Wear chemical-resistant gloves (nitrile recommended), a laboratory coat, and safety glasses or goggles at all times during handling.
• Ventilation: Conduct all weighing and dissolution steps inside a certified fume hood to minimize inhalation exposure to dust or vapors.
• Waste Disposal: Dispose of all waste materials in accordance with local institutional and governmental regulations for halogenated organic waste.
• First Aid: In case of skin or eye contact, rinse thoroughly with water for at least 15 minutes and seek medical attention as appropriate.

Storage Protocol

Proper storage is essential to maintain the integrity and reactivity of Methyl 3-iodo-1H-indole-6-carboxylate over time. The C–I bond at C-3, while robust under typical laboratory conditions, can be susceptible to degradation upon prolonged exposure to light, moisture, and atmospheric oxygen.

• Temperature: Store at 2–8 °C or at room temperature in a cool, dry location as specified on the product label. Confirm recommended temperature range from the product datasheet.
• Light: Keep in the original amber glass vial or wrap container in aluminum foil to protect from photodegradation.
• Atmosphere: After first opening, re-seal under dry inert gas (nitrogen or argon) using a rubber septum or Parafilm to prevent moisture uptake and oxidation.
• Container: Keep tightly closed in its original container when not in use. Do not transfer to incompatible plastic containers.

Check the compound visually and by TLC or HPLC before use if stored for extended periods. Discard if discoloration or unexpected decomposition is observed.

Synthetic Applications and General Reaction Protocol

Methyl 3-iodo-1H-indole-6-carboxylate is principally employed as an aryl/heteroaryl iodide electrophile in transition-metal-catalyzed cross-coupling reactions. The following general guidance applies to common reaction classes; researchers should optimize conditions for their specific substrate and target.

Suzuki–Miyaura Cross-Coupling (General Guidance)

1. Charge a dry, inert-atmosphere flask with Methyl 3-iodo-1H-indole-6-carboxylate (1.0 equiv), an arylboronic acid or ester (1.1–1.5 equiv), and a palladium catalyst (e.g., Pd(PPh₃)₄ or Pd(dppf)Cl₂, 2–5 mol%).
2. Add an appropriate base (e.g., K₂CO₃ or Cs₂CO₃, 2.0–3.0 equiv) and a degassed solvent mixture (e.g., DMF/H₂O or dioxane/H₂O, 4:1).
3. Stir the reaction mixture at 80–100 °C under nitrogen or argon atmosphere for 12–18 h, monitoring by TLC or LCMS.
4. Cool to room temperature, dilute with ethyl acetate, wash with brine, dry over MgSO₄, filter, and concentrate under reduced pressure.
5. Purify the product by column chromatography or recrystallization.

Sonogashira Coupling (General Guidance)

1. Combine Methyl 3-iodo-1H-indole-6-carboxylate (1.0 equiv), a terminal alkyne (1.1–1.5 equiv), Pd catalyst (e.g., PdCl₂(PPh₃)₂, 2–5 mol%), and CuI co-catalyst (5–10 mol%) in degassed triethylamine or DMF/Et₃N.
2. Stir at 50–80 °C under inert atmosphere until complete (typically 4–12 h).
3. Work up as above and purify by column chromatography.

Note: Protect the NH of the indole if N-substitution is not desired during coupling reactions. N-protection with Boc or SEM groups is commonly employed prior to metal-catalyzed steps.

Quality Control and Analytical Characterization

Before incorporating Methyl 3-iodo-1H-indole-6-carboxylate into a multi-step synthesis, confirm identity and purity using the following analytical techniques:

• TLC: Run on silica gel with an appropriate solvent system (e.g., hexane/EtOAc 4:1). Visualize under UV light (254 nm) or with KMnO₄ stain.
• HPLC: Reverse-phase HPLC (C18 column, acetonitrile/water gradient with 0.1% TFA) provides quantitative purity assessment. Target purity ≥95% for synthetic applications.
• ¹H NMR: Confirm the characteristic indole NH proton (broad singlet, ~8–10 ppm), C-2 vinyl proton, and aromatic protons. The absence of a C-3 proton (displaced by iodine) is diagnostic.
• Mass Spectrometry (ESI or APCI): Confirm the molecular ion consistent with the molecular formula. The isotope pattern characteristic of a mono-iodo compound (single iodine, ¹²⁷I) assists confirmation.
• Melting Point: Compare against literature or supplier certificate of analysis values where available.

Document all QC results in a laboratory notebook and retain a certificate of analysis (CoA) from Aladdin Scientific with each lot for traceability.