4-Dibenzofuranboronic acid
[CAS# 100124-06-9]

Identification

• Classification: Chemical reagent >> Organic reagent >> Boric acid
• Name: 4-Dibenzofuranboronic acid
• Synonyms: 4-(Dibenzofuranyl)boronic acid
• Molecular Formula: C₁₂H₉BO₃
• Molecular Weight: 212.01
• CAS Registry Number: 100124-06-9
• EC Number: 672-293-9
• SMILES: B(C1=C2C(=CC=C1)C3=CC=CC=C3O2)(O)O

Properties

• Density: 1.3±0.1 g/cm³, Calc.^*
• Melting point: 286-291 °C (Expl.)
• Index of Refraction: 1.701, Calc.^*
• Boiling Point: 438.5±37.0 °C (760 mmHg), Calc.^*
• Flash Point: 219.0±26.5 °C, 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
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	3	H335
Eye irritation	Eye Irrit.	2A	H319

Discovery and Applications

4-Dibenzofuranboronic acid is an organoboron compound with the molecular formula C₁₂H₉BO₃. It belongs to the class of boronic acids and features a dibenzofuran moiety substituted at the 4-position with a boronic acid group. This compound is of notable interest in synthetic organic chemistry, particularly in cross-coupling reactions, due to its structural stability and reactivity.

The dibenzofuran scaffold has been studied extensively since the early 20th century, primarily for its aromatic and planar structure, which is relevant in both materials science and pharmaceutical research. The boronic acid functionality became widely used in the latter part of the 20th century, particularly following the development of the Suzuki-Miyaura cross-coupling reaction in the late 1970s. The combination of the dibenzofuran core with a boronic acid group represents a convergence of two chemically significant motifs, enabling the synthesis of complex aromatic compounds.

4-Dibenzofuranboronic acid is typically synthesized via electrophilic borylation reactions starting from halogenated dibenzofuran precursors. Common approaches include the lithiation of 4-halodibenzofuran followed by treatment with trialkylborates, followed by hydrolysis to yield the free boronic acid. The compound is stable under standard laboratory conditions and can be handled and stored without significant degradation when kept dry and protected from light.

The primary application of 4-dibenzofuranboronic acid is in the Suzuki-Miyaura coupling reaction, a palladium-catalyzed process that forms carbon-carbon bonds between boronic acids and halogenated or pseudohalogenated aromatic compounds. This method is widely used for the synthesis of biaryl compounds, which are key components in pharmaceuticals, agrochemicals, and advanced materials. The presence of the dibenzofuran core in this boronic acid allows the introduction of this moiety into more complex molecular architectures, enhancing the rigidity and aromatic character of the final product.

In medicinal chemistry, the dibenzofuran scaffold has been incorporated into various pharmacologically active molecules, including compounds with anticancer, anti-inflammatory, and antimicrobial activity. While 4-dibenzofuranboronic acid itself is not a drug, its utility as a building block facilitates the creation of such biologically active derivatives. For example, biaryl and heterobiaryl compounds synthesized using this boronic acid may act as receptor ligands or enzyme inhibitors, depending on the nature of the coupled substituent.

In materials science, dibenzofuran-containing compounds have been investigated for their optoelectronic properties, such as use in organic light-emitting diodes (OLEDs), organic semiconductors, and liquid crystal materials. The planar and rigid nature of the dibenzofuran ring system imparts thermal and photochemical stability to materials, which is beneficial in the fabrication of durable electronic devices. 4-Dibenzofuranboronic acid serves as a key precursor in the synthesis of such materials through palladium-catalyzed coupling strategies.

The boronic acid group also enables reversible binding with diols and other hydroxyl-containing groups, which has implications in the development of sensors and recognition systems. In chemical biology and analytical chemistry, arylboronic acids have been used to construct probes for detecting saccharides and other biologically relevant molecules. While 4-dibenzofuranboronic acid has not been widely reported for this specific application, its structural features make it a candidate for exploration in such contexts.

In conclusion, 4-dibenzofuranboronic acid is a synthetically valuable organoboron compound widely utilized in cross-coupling chemistry. Its applications span pharmaceutical synthesis and materials science, owing to the stability and reactivity of both the boronic acid group and the dibenzofuran core. The compound has established utility in facilitating the formation of complex aromatic systems, contributing to the development of a wide range of functional organic molecules.

References

2012. Oxidative Trifluoromethylthiolations of Aryl Boronic Acids Using a Copper/O₂‐Based Protocol. Chemistry - An Asian Journal, 7(6).
DOI: 10.1002/asia.201200347

2012. Other Fused-Ring Hetarylboronic Acids and Derivatives. Science of Synthesis, Vol. 6.
https://science-of-synthesis.thieme.com/app/text/?id=SD-207-00092

2010. Transition-Metal-Catalyzed Oxidative Heck Reactions. Synthesis, 2010(08).
DOI: 10.1055/s-0029-1218748