6-Chloro-N-methylpyrazin-2-amine: Properties & Research Uses
6-Chloro-N-methylpyrazin-2-amine: Properties & Research Uses
6-Chloro-N-methylpyrazin-2-amine is a halogenated, nitrogen-rich heterocyclic building block widely employed in medicinal chemistry and pharmaceutical synthesis as a versatile electrophilic intermediate for the construction of bioactive pyrazine-containing scaffolds.
- IUPAC Name
- 6-Chloro-N-methylpyrazin-2-amine
- Molecular Formula
- C₅H₆ClN₃
- Molecular Weight
- 143.57 g/mol
- CAS Number
- needs_review — not confirmed in source material
- SKU
- C195280
- Functional Groups
- Aromatic C–Cl bond (electrophilic site); secondary amine (N–CH₃, nucleophilic site)
- Core Scaffold
- Pyrazine (1,4-diazine) ring
Chemical Identity and Structure
6-Chloro-N-methylpyrazin-2-amine belongs to the class of chlorinated pyrazine derivatives, a family of planar, aromatic diazines valued for their hydrogen-bond-accepting nitrogen atoms and favorable pharmacokinetic profiles. The compound features a pyrazine ring bearing a chloro substituent at position 6 and a methylamino group at position 2, creating two orthogonal reactive sites within a single, compact molecule.
The aromatic C–Cl bond is activated toward nucleophilic aromatic substitution (SNAr) due to the electron-withdrawing effect of the ring nitrogens, making it highly reactive toward amines, thiols, and alkoxides under mild conditions. Simultaneously, the secondary amine (–NHCH₃) can participate in acylation, sulfonylation, or reductive amination reactions, providing further elaboration points for library synthesis.
The pyrazine ring's two nitrogen atoms confer good aqueous solubility relative to carbocyclic analogs and contribute to favorable ADMET characteristics in drug candidates, which is a primary reason pyrazine motifs appear frequently in approved pharmaceuticals and clinical candidates.
Synthesis and Reactivity
The synthesis of 6-Chloro-N-methylpyrazin-2-amine is typically approached via selective amination of dichloropyrazine precursors. A common route involves controlled mono-substitution of 2,6-dichloropyrazine with methylamine under carefully optimized temperature and stoichiometric conditions to achieve regioselectivity at one chlorine over the other. Alternatively, directed halogenation of N-methylpyrazin-2-amine can be employed.
In downstream synthetic applications, the compound most frequently undergoes SNAr at the C6 chloro position. Typical nucleophiles include primary and secondary amines for the generation of diaminopyrazine analogs, sodium alkoxides to afford ether-linked products, and sodium thiolates to yield thioether derivatives. These transformations proceed without transition-metal catalysis under appropriate solvent and base conditions, offering practical advantages in scale-up.
Transition-metal-catalyzed cross-coupling reactions, such as Buchwald-Hartwig amination or Suzuki-Miyaura coupling, can also be performed at the C–Cl position when carbon–carbon or carbon–nitrogen bond formation with aryl partners is desired, expanding the accessible chemical space considerably.
Research and Pharmaceutical Applications
Pyrazine derivatives bearing halogen and amino substituents are recognized pharmacophoric elements encountered in kinase inhibitors, antiparasitic agents, antifungals, and CNS-active compounds. 6-Chloro-N-methylpyrazin-2-amine serves as a privileged building block enabling medicinal chemists to rapidly introduce a methylaminopyrazine core into lead structures during hit-to-lead and lead-optimization campaigns.
The compound is also used as a key intermediate in the preparation of more complex diaminopyrazine scaffolds that form the basis of several classes of protein kinase inhibitors. The methylamino group provides a hydrogen-bond donor capable of engaging hinge-region backbone carbonyls within ATP-binding pockets, a well-established binding motif in kinase pharmacology.
Beyond drug discovery, 6-Chloro-N-methylpyrazin-2-amine finds utility in agrochemical research, materials science (e.g., as a component in the synthesis of metal-organic frameworks or coordination polymers exploiting the chelating ability of pyrazine nitrogens), and as a reference compound for analytical method development.
Handling, Storage, and Safety Considerations
As with most halogenated aromatic amines, 6-Chloro-N-methylpyrazin-2-amine should be handled with appropriate personal protective equipment including nitrile gloves, safety goggles, and a laboratory coat. Operations involving weighing or dissolution of the compound should be performed in a well-ventilated fume hood to minimize inhalation exposure to dust or vapors.
The compound should be stored in a cool, dry place away from strong oxidizers, acids, and bases. Sealed containers help prevent moisture uptake and maintain reagent integrity over time. Refrigerated storage (2–8 °C) is commonly recommended for long-term preservation of purity, though specific conditions should be confirmed against the certificate of analysis supplied with each lot.
Researchers should consult the Safety Data Sheet (SDS) provided by Aladdin Scientific for comprehensive hazard classifications, first-aid measures, disposal guidance, and transport regulations before use. Waste disposal must comply with applicable local and national regulations governing halogenated organic compounds.
Frequently asked questions
What is 6-Chloro-N-methylpyrazin-2-amine used for in drug discovery?
It serves as a versatile heterocyclic building block for the construction of pyrazine-containing pharmacophores. The C6 chloro group enables SNAr or cross-coupling reactions to diversify the scaffold, while the methylamino group can engage hinge-region residues in kinase binding pockets or be further functionalized, making it particularly valuable in kinase inhibitor programs and hit-to-lead campaigns.
How should I store 6-Chloro-N-methylpyrazin-2-amine to maintain its purity?
Store the compound in a tightly sealed container in a cool, dry location away from moisture, strong oxidizers, and direct light. Refrigerated storage at 2–8 °C is generally recommended for long-term stability. Always verify specific storage conditions on the Certificate of Analysis (CoA) provided with your lot from Aladdin Scientific.
Can the C–Cl bond in 6-Chloro-N-methylpyrazin-2-amine undergo transition-metal-catalyzed cross-coupling?
Yes. The aryl C–Cl bond is compatible with palladium-catalyzed reactions including Suzuki-Miyaura coupling for C–C bond formation and Buchwald-Hartwig amination for C–N bond formation. These reactions typically require a suitable palladium precatalyst, phosphine ligand, and base, and their optimization may depend on the specific coupling partner and scale.
What makes the pyrazine ring advantageous over other heterocycles in medicinal chemistry?
The pyrazine ring offers two hydrogen-bond-accepting ring nitrogens positioned para to each other, improving aqueous solubility and enabling bidentate interactions with biological targets. Its planar aromatic system supports π-stacking interactions, and the ring's electron-deficient character activates C–Cl bonds toward SNAr, facilitating rapid analog synthesis without metal catalysis.
References
- Joule, J. A.; Mills, K. Heterocyclic Chemistry, 5th ed.; Wiley-Blackwell: Oxford, 2010. (General reference on pyrazine chemistry and SNAr reactivity.)
- Roughley, S. D.; Jordan, A. M. The Medicinal Chemist's Toolbox: An Analysis of Reactions Used in the Pursuit of Drug Candidates. J. Med. Chem. 2011, 54, 3451–3479. (Discusses prevalence of SNAr and cross-coupling in drug discovery.) doi:10.1021/jm200187y
- Küenburg, B. et al. Development of a Pilot-Scale Synthesis of the Antiparasitic Agent... (Placeholder: pyrazine intermediates in API synthesis — specific reference needs verification.)
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