2‑Bromo‑6‑methoxybenzothiazole is a halogenated benzothiazole derivative with the molecular formula C8H6BrNOS (CAS 2941‑58‑4). It is a light-yellow to orange solid, used as an intermediate in organic synthesis and pharmaceutical research. The bromine atom at the 2‑position makes it reactive in cross-coupling reactions, while the methoxy group at the 6‑position modulates electronic properties and influences its reactivity and solubility.
This compound is often prepared via a Sandmeyer-type reaction, where 2‑amino‑6‑methoxybenzothiazole undergoes diazotization and is converted to the bromo derivative using copper(I) bromide. This route provides relatively direct access from the corresponding amino precursor, leveraging well-known diazonium chemistry. In practice, the amino starting material is treated with a nitrite source under acidic conditions to generate a diazonium salt, which is then substituted by bromide in the presence of a copper catalyst.
In synthetic chemistry, 2‑Bromo‑6‑methoxybenzothiazole serves as a versatile building block. The bromine can be replaced or used in palladium- or nickel-catalyzed cross-coupling reactions (such as Suzuki or Buchwald–Hartwig couplings) to introduce a variety of substituents, expanding the benzothiazole scaffold. The presence of the methoxy substituent confers electron-donating character, which may influence the reactivity in these transformations and affect the physicochemical properties of the resulting derivatives.
Benzothiazole derivatives are widely studied in medicinal chemistry for their diverse biological activities. Although no peer-reviewed study focuses exclusively on 2‑Bromo‑6‑methoxybenzothiazole, related methoxy- and amine-substituted benzothiazoles have been reported to exhibit anticancer, antibacterial, and antioxidant properties. Researchers often use substituted benzothiazoles as scaffolds when designing small molecules that can interact with biological targets, including enzymes, receptors, and nucleic acids. Because of this, the bromo-methoxy derivative is considered a useful intermediate for drug discovery and development.
From a practical lab‑handling perspective, the compound should be stored under inert gas (e.g., nitrogen or argon) in dry conditions to avoid degradation or side reactions, since the brominated heterocycle might undergo undesired substitution or hydrolysis. It is reasonably stable in common organic solvents, and purification is often achieved by silica gel chromatography following reaction.
In summary, 2‑Bromo‑6‑methoxybenzothiazole is a synthetically valuable halogenated benzothiazole intermediate. Its functional groups make it well-suited for cross-coupling and derivatization, and it serves as a platform for generating biologically active benzothiazole derivatives and other functional heterocycles.
References
Zhilitskaya LV, Yarosh NO (2021) Synthesis of biologically active derivatives of 2‑aminobenzothiazole. *Chemistry of Heterocyclic Compounds* 57(4) 369–373 DOI: 10.1007/s10593-021-02914-6
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