2,3-Dichloro-6-methoxyquinoxaline
[CAS# 39267-04-4]

Identification

• Classification: Chemical reagent >> Organic reagent >> Aromatic hydrocarbon reagent
• Name: 2,3-Dichloro-6-methoxyquinoxaline
• Molecular Formula: C₉H₆Cl₂N₂O
• Molecular Weight: 229.06
• CAS Registry Number: 39267-04-4
• EC Number: 806-741-3
• SMILES: COC1=CC2=C(C=C1)N=C(C(=N2)Cl)Cl

Properties

• Density: 1.5±0.1 g/cm³ Calc.^*
• Boiling point: 312.6±37.0 °C 760 mmHg (Calc.)^*
• Flash point: 142.9±26.5 °C (Calc.)^*
• Index of refraction: 1.638 (Calc.)^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H315-H319-H335
• Safety Statements: P261-P264-P264+P265-P271-P280-P302+P352-P304+P340-P305+P351+P338-P319-P321-P332+P317-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Eye irritation	Eye Irrit.	2	H319
Skin irritation	Skin Irrit.	2	H315
Specific target organ toxicity - single exposure	STOT SE	3	H335

Discovery and Applications

2,3‑Dichloro‑6‑methoxyquinoxaline is a halogenated quinoxaline derivative in which chlorine atoms occupy the 2‑ and 3‑positions of the quinoxaline ring and a methoxy group is present at the 6‑position. The quinoxaline core (a bicyclic system comprised of a benzene ring fused to a pyrazine ring) is a common scaffold in medicinal chemistry due to its planar aromatic nature and ability to engage in π-π interactions, hydrogen bonding, and other non‑covalent interactions. The dichloro substitution makes the molecule particularly reactive in nucleophilic aromatic substitution (SNAr) chemistry, while the methoxy substituent modulates the electron density of the ring and can influence both reactivity and solubility.

In synthesis, one plausible route to 2,3-dichloroquinoxalines involves the reaction of quinoxaline-2,3(1H,4H)-dione with phosphoryl chloride (POCl₃) under reflux, converting hydroxyl or keto functionalities at the 2 and 3 positions into chloro substituents. Following this, the methoxy group could be introduced via electrophilic substitution on the benzene portion of the quinoxaline ring—though detailed published procedures for specifically 6-methoxy substitution are limited.

Applications of substituted dichloroquinoxalines include their use as intermediates in the synthesis of biologically active compounds. Quinoxaline derivatives are found in pharmaceuticals, agrochemicals, and functional materials, acting as building blocks for further elaboration. The dichloro functionality allows coupling or substitution to generate derivatives with tailored properties, while the methoxy group might enhance lipophilicity or adjust electronic properties, influencing binding to biological targets.

In practical handling, 2,3‑dichloro‑6‑methoxyquinoxaline is likely to be handled under dry conditions because of the sensitivity of chloroquinoxalines to hydrolysis or decomposition. It would dissolve in common organic solvents and can be purified by standard methods (recrystallization or chromatography) after synthesis or substitution reactions.

Because there is a lack of peer‑reviewed articles specifically on 2,3-dichloro-6-methoxyquinoxaline, it is primarily documented in chemical catalogues and databases as a synthetic intermediate rather than as a final active compound.

References

Synfacts (2019) Synthesis of Grazoprevir. Synfacts 15 01 DOI: 10.1055/s-0037-1612028

Synfacts (2013) Synthesis of MK-5172. Synfacts 09 10 DOI: 10.1055/s-0033-1339864

Chemistry of Heterocyclic Compounds (1976) Investigation of heterocyclic quinones. Chemistry of Heterocyclic Compounds 12 1767–1772 DOI: 10.1007/bf00476731