5-Bromo-6-methylindoline-2,3-dione: Properties & Applications

5-Bromo-6-methylindoline-2,3-dione is a halogenated isatin analogue featuring both a bromine substituent at the 5-position and a methyl group at the 6-position of the indoline-2,3-dione scaffold, making it a versatile heterocyclic building block for pharmaceutical and materials research.

Chemical Name

5-Bromo-6-methylindoline-2,3-dione

SKU / Catalog Number

B189572

Core Scaffold

Indoline-2,3-dione (isatin)

Key Substituents

5-Bromo, 6-Methyl

Compound Class

Halogenated heterocyclic intermediate

Primary Research Use

Pharmaceutical synthesis, medicinal chemistry, materials science

Chemical Structure and Identity

5-Bromo-6-methylindoline-2,3-dione belongs to the isatin (indoline-2,3-dione) family of bicyclic compounds, comprising a benzene ring fused to a five-membered ring containing two carbonyl groups at positions 2 and 3. The parent isatin scaffold is itself a well-established heterocycle with a broad history in synthetic and medicinal chemistry.

In this derivative, a bromine atom occupies the 5-position of the aromatic ring, while a methyl group is located at the 6-position. These two substituents act in concert to modulate the electronic density and steric profile of the molecule: the electron-withdrawing bromine enhances electrophilicity at the carbonyl centres, while the methyl group introduces mild electron donation and steric bulk to the adjacent ring position. Together, they differentiate this compound from simpler mono-substituted isatins and provide orthogonal handles for further chemical elaboration.

Physicochemical Properties

As a solid aromatic heterocycle bearing both carbonyl and C–Br functional groups, 5-Bromo-6-methylindoline-2,3-dione is expected to display the characteristic orange-to-red coloration typical of isatin derivatives, arising from the extended conjugation of the bicyclic dione system. The presence of the bromine atom increases molecular weight relative to the unsubstituted or methyl-only analogues and lowers the compound's susceptibility to certain oxidative degradation pathways.

The two carbonyl moieties at C-2 and C-3 confer significant reactivity: C-3 (the ketone carbonyl) is particularly electrophilic and participates readily in condensation reactions with primary amines, hydrazines, hydroxylamines, and active methylene compounds. The C–Br bond at the 5-position is available for transition-metal-catalysed cross-coupling reactions such as Suzuki–Miyaura, Sonogashira, and Buchwald–Hartwig couplings, enabling rapid diversification of the core scaffold.

Researchers should store this compound in a cool, dry environment away from light and moisture, consistent with standard protocols for halogenated carbonyl compounds, to maintain long-term stability.

Synthesis and Preparation Routes

Isatin derivatives bearing halo and alkyl substituents on the benzo ring are generally accessible through several established synthetic strategies. The most classical approach starts from the corresponding aniline—in this case 2-bromo-4-methylaniline or its regioisomeric equivalent—via the Sandmeyer–Baeyer isatin synthesis or the Claisen modification. In these methods, the aniline is first condensed with chloral hydrate and hydroxylamine to form an isonitrosoacetanilide intermediate, which is then cyclised under acid conditions to yield the isatin directly.

Alternatively, directed ortho-metalation or halogenation of pre-formed 6-methylisatin can introduce the bromine substituent regioselectively at the 5-position, leveraging the directing effects of the existing methyl and carbonyl groups. Transition-metal-catalysed C–H activation strategies represent a more modern, though less routinely employed, avenue for late-stage halogenation of isatin cores.

When purchasing 5-Bromo-6-methylindoline-2,3-dione (B189572) from Aladdin Scientific, researchers receive a characterised material with defined purity, avoiding the need to perform multistep de novo synthesis and allowing direct use in downstream reactions.

Research Applications

The isatin scaffold is one of the most prolific frameworks in medicinal chemistry, and substituted isatins such as 5-Bromo-6-methylindoline-2,3-dione serve as key intermediates in the preparation of diverse bioactive compound libraries. The C-3 carbonyl position is routinely exploited for the synthesis of Schiff bases (3-imino derivatives), spiroxindoles, spirooxindoles, and 3-substituted oxindoles, many of which have been investigated for antimicrobial, antifungal, antiviral, anti-inflammatory, and anticancer activities in the published literature.

The 5-bromo substituent provides a valuable handle for palladium-catalysed cross-coupling reactions, enabling the rapid introduction of aryl, heteroaryl, vinyl, or alkynyl groups to generate structurally diverse analogues for structure–activity relationship (SAR) studies. This dual functionality—reactive carbonyl and cross-coupling-amenable C–Br bond—makes 5-Bromo-6-methylindoline-2,3-dione particularly attractive for combinatorial and parallel synthesis platforms.

Beyond medicinal chemistry, isatin derivatives have found use in the synthesis of functional dyes, fluorescent probes, and organic electronic materials, where the electron-deficient dione unit participates in donor–acceptor architectures relevant to organic photovoltaics and sensors.

Handling, Safety, and Storage

As with all brominated aromatic carbonyl compounds, appropriate laboratory precautions should be observed when handling 5-Bromo-6-methylindoline-2,3-dione. Researchers are advised to wear suitable personal protective equipment (PPE) including laboratory coat, nitrile gloves, and safety glasses. Work should be conducted in a well-ventilated area or fume hood to minimise inhalation exposure to fine particulates.

The compound should be stored in a tightly sealed container, in a cool and dry location away from direct light, heat sources, and incompatible reagents such as strong oxidisers and strong bases. These precautions are consistent with standard laboratory practice for solid organic intermediates containing halogen and carbonyl functional groups.

For specific safety data including GHS hazard classifications, first-aid measures, and disposal instructions, users should consult the Safety Data Sheet (SDS) provided by Aladdin Scientific for product B189572 prior to use.

Frequently asked questions

What is 5-Bromo-6-methylindoline-2,3-dione used for in research?

5-Bromo-6-methylindoline-2,3-dione is primarily used as a heterocyclic building block in medicinal chemistry and organic synthesis. Its reactive C-3 carbonyl enables condensation reactions to form Schiff bases, spirooxindoles, and related scaffolds, while the 5-bromo substituent is amenable to palladium-catalysed cross-coupling reactions for structural diversification.

How should 5-Bromo-6-methylindoline-2,3-dione (B189572) be stored?

The compound should be stored in a tightly sealed container in a cool, dry place away from light, heat, and incompatible reagents such as strong oxidisers and strong bases. These conditions help preserve chemical integrity over the long term. Always refer to the Aladdin Scientific SDS for product B189572 for full storage guidance.

What cross-coupling reactions can be performed using the bromo substituent of this compound?

The 5-bromo group on 5-Bromo-6-methylindoline-2,3-dione is suitable for a range of palladium-catalysed cross-coupling reactions, including Suzuki–Miyaura (with arylboronic acids), Sonogashira (with terminal alkynes), and Buchwald–Hartwig (for C–N bond formation) couplings. These transformations allow researchers to introduce diverse substituents and rapidly build compound libraries for SAR studies.

How does the methyl group at the 6-position affect the reactivity of this isatin derivative?

The 6-methyl group introduces mild electron-donating character and steric bulk to the aromatic ring adjacent to the 5-bromo substituent. This can influence regioselectivity in electrophilic aromatic substitution reactions and affect the electronic environment of the C-3 carbonyl, potentially modulating condensation reaction rates and the physicochemical properties of the resulting products.

References

1. Vine, K. L. et al. An investigation into the cytotoxicity and mode of action of some novel N-alkyl-substituted isatins. Journal of Medicinal Chemistry. Review-level background on isatin bioactivity. Specific volume, page, and year not confirmed from source material.
2. Bal, T. R. et al. Synthesis and antimicrobial activity of some Schiff bases derived from isatins. General reference for isatin Schiff base chemistry; specific bibliographic details not confirmed from source material.
3. Clayden, J.; Greeves, N.; Warren, S. Organic Chemistry, 2nd ed. Oxford University Press, 2012. Textbook-level reference for carbonyl reactivity and cross-coupling chemistry.

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