6-Bromo-1-methyl-1,2,3,4-tetrahydroquinolin-2-one: Handling & Use Protocol

6-bromo-1-methyl-1,2,3,4-tetrahydroquinolin-2-one is a brominated bicyclic lactam building block widely employed as a versatile synthetic intermediate in medicinal chemistry and heterocyclic synthesis.

Product SKU

B626828

Chemical Name

6-bromo-1-methyl-1,2,3,4-tetrahydroquinolin-2-one

Compound Class

Brominated bicyclic lactam (tetrahydroquinolinone)

Primary Application

Synthetic intermediate and building block in medicinal and heterocyclic chemistry

Recommended Storage

Cool, dry, dark conditions; sealed container away from moisture

Solubility (General)

Soluble in common organic solvents (e.g., DMSO, DCM, DMF); low aqueous solubility expected for this lipophilic lactam

Compound Overview and Chemical Properties

6-Bromo-1-methyl-1,2,3,4-tetrahydroquinolin-2-one (SKU: B626828) is a bicyclic compound featuring a partially saturated six-membered nitrogen-containing ring fused to a benzene ring. The lactam carbonyl at position 2 and the N-methyl substituent at position 1 define its reactivity profile, while the bromine at position 6 on the aromatic ring provides a versatile handle for transition-metal-catalyzed cross-coupling reactions such as Suzuki–Miyaura, Buchwald–Hartwig, and Sonogashira couplings.

The tetrahydroquinolinone scaffold is recognized in medicinal chemistry as a privileged structure associated with diverse biological activities. The N-methyl group reduces hydrogen-bond donor capacity, potentially improving membrane permeability relative to the N-H parent compound. Researchers should handle all brominated aromatic compounds with appropriate care, as detailed in the safety section below.

Safety and Handling Precautions

Prior to working with 6-bromo-1-methyl-1,2,3,4-tetrahydroquinolin-2-one, consult the Safety Data Sheet (SDS) supplied by Aladdin Scientific. In the absence of specific toxicological data for this compound, apply standard precautionary principles for reactive organic intermediates containing halogen substituents:

• Personal Protective Equipment (PPE): Wear nitrile gloves, a laboratory coat, and safety goggles at all times during handling.
• Ventilation: Work in a well-ventilated fume hood to avoid inhalation of dust or vapors.
• Skin and Eye Contact: Avoid direct contact. In case of skin contact, wash immediately with soap and water for at least 15 minutes. In case of eye contact, rinse with copious water and seek medical attention.
• Ingestion/Inhalation: Do not eat, drink, or smoke in the laboratory. If inhaled, move to fresh air immediately.
• Disposal: Dispose of waste material in accordance with local, regional, and national regulations for halogenated organic compounds.

Store the compound in a tightly sealed container under cool, dry, and dark conditions to prevent decomposition or moisture uptake.

Solution Preparation and Solubility Protocol

Follow the steps below to prepare stock solutions of 6-bromo-1-methyl-1,2,3,4-tetrahydroquinolin-2-one for downstream synthetic or assay use:

1. Equilibrate to room temperature: Allow the sealed vial to equilibrate to ambient temperature before opening to prevent condensation on the solid.
2. Select solvent: Based on the lipophilic character of the tetrahydroquinolinone scaffold, dimethyl sulfoxide (DMSO), dichloromethane (DCM), N,N-dimethylformamide (DMF), tetrahydrofuran (THF), or ethyl acetate are recommended as primary solvents. Aqueous solubility is expected to be low; aqueous buffer solutions are generally not recommended without a co-solvent.
3. Weigh accurately: Using an analytical balance, tare a clean, dry microcentrifuge tube or glass vial. Transfer the desired mass of compound using a stainless-steel spatula.
4. Add solvent incrementally: Add a portion of the chosen solvent, cap the vessel, and vortex or sonicate briefly (30–60 seconds) until complete dissolution is observed. Add additional solvent to reach the target concentration.
5. Verify dissolution: Visually confirm that the solution is clear and free of particulates before use. If necessary, filter through a 0.2 µm PTFE syringe filter.
6. Label and store: Label with compound name, concentration, solvent, date, and operator initials. Store stock solutions under inert atmosphere (N₂ or Ar) at –20 °C for extended stability.

Note: Actual solubility values have not been independently verified for this specific compound. Conduct a small-scale solubility test before preparing large-volume stocks.

Synthetic Applications and Cross-Coupling Reactions

The C6-bromo substituent on the aromatic ring of 6-bromo-1-methyl-1,2,3,4-tetrahydroquinolin-2-one makes it an excellent electrophilic partner in a range of palladium- and copper-catalyzed transformations commonly used to elaborate the tetrahydroquinolinone core:

• Suzuki–Miyaura Coupling: React with aryl- or heteroarylboronic acids/esters in the presence of a Pd catalyst (e.g., Pd(PPh₃)₄ or Pd(dppf)Cl₂) and base (e.g., K₂CO₃) in aqueous dioxane or DMF to install biaryl motifs.
• Buchwald–Hartwig Amination: Employ Pd₂(dba)₃ with a bulky phosphine ligand (e.g., BINAP or XPhos) to form C–N bonds, converting the aryl bromide to arylamines.
• Sonogashira Coupling: Couple with terminal alkynes using Pd/Cu co-catalysis to introduce alkynyl groups onto the aromatic ring.
• Miyaura Borylation: Convert the aryl bromide to the corresponding arylboronic acid pinacol ester using bis(pinacolato)diboron (B₂pin₂) and Pd catalysis, generating a new coupling partner.

General reaction setup: Degas solvents by sparging with N₂ or Ar for 15 minutes prior to use. Use Schlenk technique or a glovebox for air-sensitive catalysts. Monitor reaction progress by TLC or LCMS.

Specific reaction conditions, yields, and scope for this exact compound have not been independently validated. All conditions described are general literature precedents for analogous aryl bromide substrates and require optimization.

Quality Control and Verification

Upon receipt of 6-bromo-1-methyl-1,2,3,4-tetrahydroquinolin-2-one (B626828) from Aladdin Scientific, perform the following identity and purity checks before use in critical applications:

• Visual Inspection: Confirm the compound appears as a solid consistent with the expected physical form. Note any discoloration, caking, or unusual odor and contact Aladdin Scientific technical support if anomalies are observed.
• ¹H NMR Analysis: Dissolve a small quantity (5–10 mg) in deuterated DMSO (DMSO-d₆) or CDCl₃ and record a ¹H NMR spectrum at 400 MHz or higher. Expected key signals include: aromatic protons in the 7.0–7.6 ppm region (consistent with a 1,2,4-trisubstituted bromobenzene pattern), N-CH₃ singlet near 3.3–3.5 ppm, and methylene protons (CH₂–CH₂) in the 2.5–3.0 ppm region. Compare against the certificate of analysis (CoA).
• HPLC Purity: Analyze by reverse-phase HPLC (C18 column, acetonitrile/water gradient) to confirm purity meets the specification stated on the CoA.
• Mass Spectrometry: Confirm molecular ion consistent with the molecular formula. The compound contains one bromine atom, so the characteristic M and M+2 isotope pattern (approximately 1:1 ratio) should be observed in the mass spectrum.

Specific NMR chemical shift values and exact purity specifications are not confirmed in the available source material. Refer to the product CoA supplied with each lot for authoritative data.

Frequently asked questions

What solvents are suitable for dissolving 6-bromo-1-methyl-1,2,3,4-tetrahydroquinolin-2-one?

Based on the lipophilic nature of the tetrahydroquinolinone scaffold, organic solvents such as DMSO, DCM, DMF, THF, and ethyl acetate are generally recommended. Aqueous solubility is expected to be limited; a co-solvent should be used if aqueous media are required. Always perform a small-scale solubility test before preparing large stock solutions.

What cross-coupling reactions can be performed using the aryl bromide of this compound?

The C6 aryl bromide is suitable for a range of palladium- and copper-catalyzed reactions, including Suzuki–Miyaura coupling with boronic acids, Buchwald–Hartwig amination, Sonogashira coupling with terminal alkynes, and Miyaura borylation. These transformations allow installation of aryl, heteroaryl, amino, alkynyl, and boronate ester groups onto the aromatic ring. Reaction conditions require optimization for this specific substrate.

How should 6-bromo-1-methyl-1,2,3,4-tetrahydroquinolin-2-one be stored to ensure stability?

The compound should be stored in a tightly sealed container under cool, dry, and dark conditions to prevent moisture uptake and photodegradation. For stock solutions, storage at –20 °C under an inert atmosphere (N₂ or Ar) is recommended. Always allow the vial to equilibrate to room temperature before opening to avoid condensation.

How can I confirm the identity and purity of the received compound?

Identity can be confirmed by ¹H NMR spectroscopy (look for the characteristic aromatic, N-CH₃, and methylene signals) and by mass spectrometry (confirm the molecular ion with the diagnostic M and M+2 bromine isotope pattern). Purity should be assessed by reverse-phase HPLC and compared against the certificate of analysis (CoA) provided with each lot by Aladdin Scientific.

What personal protective equipment is required when handling this compound?

At minimum, wear nitrile gloves, a laboratory coat, and safety goggles when handling 6-bromo-1-methyl-1,2,3,4-tetrahydroquinolin-2-one. All operations should be performed in a well-ventilated fume hood. Consult the SDS for complete hazard information before use.

References

1. Clayden, J.; Greeves, N.; Warren, S. Organic Chemistry, 2nd ed.; Oxford University Press: Oxford, 2012. General reference for lactam chemistry and cross-coupling reactions.
2. Joule, J. A.; Mills, K. Heterocyclic Chemistry, 5th ed.; Wiley-Blackwell: Oxford, 2010. Reference for tetrahydroquinolinone scaffold chemistry.
3. Miyaura, N.; Suzuki, A. Palladium-Catalyzed Cross-Coupling Reactions of Organoboron Compounds. Chem. Rev. 1995, 95, 2457–2483. General reference for Suzuki–Miyaura coupling applicable to aryl bromide substrates. doi:10.1021/cr00039a007
4. Hartwig, J. F. Palladium-Catalyzed Amination of Aryl Halides: Mechanism and Rational Catalyst Design. Acc. Chem. Res. 1998, 31, 852–860. General reference for Buchwald–Hartwig amination. doi:10.1021/ar9600108

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