6-Bromo-3-Chloroisoquinoline: Handling & Application Guide

6-bromo-3-chloroisoquinoline is a dihalogenated isoquinoline building block widely employed in transition-metal-catalysed cross-coupling reactions and heterocyclic synthesis for drug discovery and materials research.

CAS-style Name

6-bromo-3-chloroisoquinoline

SKU

B193894

Molecular Formula

C₉H₅BrClN

Molecular Weight

242.50 g/mol

Key Functional Handles

C-3 chloro (more electrophilic, selective SNAr/coupling) and C-6 bromo (selective metal-catalysed coupling)

Recommended Storage

Cool, dry place; sealed container away from moisture and light

Chemical Identity and Structural Features

6-Bromo-3-chloroisoquinoline (Aladdin SKU: B193894) belongs to the isoquinoline family of bicyclic aromatic nitrogen heterocycles. The compound carries two distinct halogen substituents: a chlorine atom at the 3-position and a bromine atom at the 6-position. This differentiated halogenation pattern is synthetically valuable because the two halogens exhibit different reactivity profiles under standard organometallic conditions.

The C-3 chloro group is activated toward nucleophilic aromatic substitution (SNAr) and certain palladium-catalysed processes due to the electron-withdrawing effect of the ring nitrogen at the 2-position. The C-6 bromo group is typically more reactive in Pd(0)- or Ni-catalysed cross-coupling reactions (e.g., Suzuki–Miyaura, Negishi, Buchwald–Hartwig) under mild conditions, allowing sequential functionalisation of the two positions. This orthogonal reactivity makes 6-bromo-3-chloroisoquinoline a versatile di-functional building block for constructing complex molecular architectures.

Recommended Applications and Synthetic Protocols

Suzuki–Miyaura Cross-Coupling (C-6 position): The C-6 bromo bond undergoes efficient Suzuki coupling with aryl- or heteroarylboronic acids or esters. A typical protocol employs Pd(PPh₃)₄ or Pd(dppf)Cl₂ as catalyst (1–5 mol%), K₂CO₃ or Cs₂CO₃ as base, and a mixture of toluene/ethanol/water or DMF/water as solvent at 80–100 °C under nitrogen atmosphere. Reaction times of 2–12 hours are typical. The C-3 chloro group can remain intact under these conditions, providing a handle for subsequent transformation.

Buchwald–Hartwig Amination (C-3 or C-6 position): Palladium catalysts bearing bulky phosphine ligands (e.g., BINAP, SPhos, XPhos) enable C–N bond formation at either halogen site. Selective amination at C-3 is accessible under certain ligand/base combinations owing to the enhanced electrophilicity at that position.

SNAr at C-3: Nitrogen- or oxygen-centred nucleophiles (amines, alkoxides) can displace the C-3 chloride under thermal conditions (DMF or DMSO solvent, 60–120 °C) or with mild base (K₂CO₃, Et₃N), often without requiring a metal catalyst.

Sequential Functionalisation: A common synthetic strategy involves (1) selective Suzuki coupling at C-6 to introduce an aryl or heteroaryl group, followed by (2) SNAr or Pd-catalysed amination at C-3 to install an amine or other nucleophile, yielding highly functionalised isoquinoline derivatives relevant to medicinal chemistry programmes.

Handling, Safety and Storage Guidelines

Personal Protective Equipment (PPE): When handling 6-bromo-3-chloroisoquinoline, wear appropriate laboratory PPE including nitrile gloves, a lab coat, and safety goggles. Work in a well-ventilated area or a fume hood to avoid inhalation of dust or vapours.

Storage: Store the compound in a tightly sealed container in a cool, dry location away from direct light, moisture, and incompatible materials (strong oxidisers, strong bases). Refrigerated storage (2–8 °C) may be appropriate for long-term preservation of purity. Always confirm storage conditions on the Certificate of Analysis (CoA) supplied with the product.

Handling Precautions: Avoid contact with skin, eyes, and clothing. In case of skin contact, wash thoroughly with soap and water. In case of eye contact, rinse with copious water for at least 15 minutes and seek medical advice. As with all fine chemicals of unknown complete toxicological profile, treat as potentially harmful and follow your institution's chemical hygiene plan.

Waste Disposal: Dispose of waste material in accordance with local, national, and institutional regulations governing halogenated organic compounds.

Quality, Purity and Specification Considerations

For synthetic and medicinal chemistry applications, the purity of 6-bromo-3-chloroisoquinoline is critical to achieving reproducible reaction outcomes. Aladdin Scientific supplies this compound (SKU: B193894) with purity specifications documented in the accompanying Certificate of Analysis (CoA).

Purity Assessment Methods: Purity is typically assessed by high-performance liquid chromatography (HPLC) or gas chromatography (GC), supported by NMR spectroscopic characterisation (¹H NMR, ¹³C NMR) to confirm structural identity. Halogen content may additionally be verified by elemental analysis.

Identity Confirmation: Researchers should verify the identity of the received material against the expected spectral data prior to use in sensitive applications. Key NMR indicators include distinct aromatic proton signals consistent with the isoquinoline ring system and the respective halogen substitution pattern.

Batch Traceability: Each batch is assigned a unique lot number. Researchers are advised to record the lot number in experimental notebooks to ensure traceability and reproducibility across experiments.

Frequently asked questions

What is the difference in reactivity between the C-3 chloro and C-6 bromo groups in 6-bromo-3-chloroisoquinoline?

The C-6 bromo group is generally more reactive in palladium- or nickel-catalysed cross-coupling reactions (such as Suzuki–Miyaura coupling) under mild conditions, while the C-3 chloro group, activated by the adjacent ring nitrogen, is more susceptible to nucleophilic aromatic substitution (SNAr) and can also participate in metal-catalysed couplings. This orthogonal reactivity allows chemists to functionalise each position selectively in a stepwise manner.

How should 6-bromo-3-chloroisoquinoline (B193894) be stored to maintain its purity?

The compound should be stored in a tightly sealed container in a cool, dry place, protected from moisture and direct light. Refrigerated storage at 2–8 °C is recommended for long-term use. Always consult the Certificate of Analysis provided with the specific batch for confirmed storage conditions.

Can 6-bromo-3-chloroisoquinoline be used in Buchwald–Hartwig amination reactions?

Yes. Buchwald–Hartwig amination can be performed at either the C-3 chloro or C-6 bromo position using palladium catalysts with bulky phosphine ligands such as BINAP, SPhos, or XPhos. Selective amination at C-3 is often facilitated by its higher electrophilicity relative to C-6. Optimisation of ligand, base, and solvent is recommended for each specific substrate combination.

Is 6-bromo-3-chloroisoquinoline relevant to drug discovery research?

Yes. Isoquinoline scaffolds are well-established pharmacophores found in numerous bioactive natural products and synthetic drug candidates. The dual halogen handles on 6-bromo-3-chloroisoquinoline make it a versatile intermediate for rapidly building structural diversity around the isoquinoline core, which is highly valuable in medicinal chemistry and fragment-based drug discovery programmes.

References

1. Miyaura, N.; Suzuki, A. Palladium-Catalyzed Cross-Coupling Reactions of Organoboron Compounds. Chemical Reviews 1995, 95, 2457–2483. doi:10.1021/cr00039a007
2. Wolfe, J. P.; Wagaw, S.; Marcoux, J.-F.; Buchwald, S. L. Rational Development of Practical Catalysts for Aromatic Carbon–Nitrogen Bond Formation. Accounts of Chemical Research 1998, 31, 805–818. doi:10.1021/ar9600650
3. Clayden, J.; Greeves, N.; Warren, S. Organic Chemistry, 2nd ed.; Oxford University Press: Oxford, 2012. (General reference for SNAr and cross-coupling mechanisms.)

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