2,4,4,5,5-Pentamethyl-1,3,2-dioxaborolane: FAQs & Uses

2,4,4,5,5-Pentamethyl-1,3,2-dioxaborolane is a cyclic boronic ester reagent widely employed in organic synthesis as a boron source for hydroboration reactions and the preparation of structurally defined boronate esters.

Chemical Name

2,4,4,5,5-Pentamethyl-1,3,2-dioxaborolane

CAS / Source

TCI P2602 (source reference)

Compound Class

Cyclic boronic ester (1,3,2-dioxaborolane derivative)

Primary Use

Hydroboration reactions and organoboron synthesis

Key Structural Feature

Five methyl substituents on the dioxaborolane ring providing steric and electronic modulation

Aladdin SKU

P404927

What Is 2,4,4,5,5-Pentamethyl-1,3,2-dioxaborolane?

2,4,4,5,5-Pentamethyl-1,3,2-dioxaborolane is a five-membered cyclic boronic ester in which the boron atom is incorporated into a 1,3,2-dioxaborolane ring bearing five methyl groups at the 2-, 4-, 4-, 5-, and 5-positions. This substitution pattern confers significant steric shielding around the boron center, modulating its Lewis acidity and reactivity relative to simpler boronate esters.

The compound belongs to the broader family of organoboron reagents that have become indispensable tools in modern synthetic chemistry. Its structural relationship to pinacol borane and related neopentyl glycol borane derivatives makes it a useful reference point when selecting boron reagents for specific transformations.

Key Physical and Chemical Properties

As a cyclic boronic ester, 2,4,4,5,5-Pentamethyl-1,3,2-dioxaborolane is typically encountered as a colorless to pale yellow liquid or low-melting solid at ambient conditions, though researchers should consult the product specification sheet for confirmed physical data. The boron atom in this compound is sp2-hybridized with an empty p-orbital, making it electrophilic and capable of coordinate-covalent bond formation with Lewis bases.

The geminal dimethyl groups on the carbon backbone (positions 4,4 and 5,5) contribute to the hydrolytic stability of the ester linkage by the Thorpe–Ingold effect, while also protecting the boron center from rapid protodeboronation under mildly aqueous conditions. Storage under inert atmosphere (nitrogen or argon) and at reduced temperature is generally recommended to maintain reagent integrity.

Synthetic Applications in Organoboron Chemistry

Cyclic boronic esters of the 1,3,2-dioxaborolane type, including pentamethyl-substituted variants, serve multiple roles in synthetic workflows. They can act as boron-transfer agents for transesterification with other diols, enabling the controlled exchange of boronic ester protecting groups. They are also relevant as intermediates or reference compounds in the preparation of more complex boronate esters used in Suzuki–Miyaura cross-coupling reactions.

In hydroboration contexts, related boranes derived from this ester framework have been explored for additions across unsaturated C–C bonds, yielding alkyl- or alkenyl-boronic ester products that serve as versatile handles for subsequent functionalization. The steric profile imparted by the five methyl groups influences regioselectivity, making careful reagent selection important.

Researchers engaged in medicinal chemistry, materials science, and total synthesis may encounter this compound as a boron-protecting group or as a building block for boron-containing pharmacophores and functional materials.

Safe Handling, Storage and Disposal

Organoboron esters should be handled with standard laboratory precautions. Use appropriate personal protective equipment including chemical-resistant gloves, safety goggles, and a laboratory coat. Operations involving significant quantities or volatile fractions should be conducted in a well-ventilated fume hood. Avoid contact with water or moisture during handling to minimize hydrolysis and potential generation of boric acid and the corresponding diol.

Store the reagent in a tightly sealed container under inert gas, away from light, heat, and incompatible materials such as strong oxidizing agents and strong bases. Consult the product Safety Data Sheet (SDS) for compound-specific hazard classifications, first-aid measures, and regulatory disposal requirements applicable to your jurisdiction.

Ordering and Availability at Aladdin Scientific

2,4,4,5,5-Pentamethyl-1,3,2-dioxaborolane is available from Aladdin Scientific under SKU P404927, sourced with reference to TCI P2602. Researchers can place orders directly through the Aladdin Scientific website, or contact the sales team for bulk pricing, custom pack sizes, and institutional procurement arrangements.

For questions regarding purity specifications, certificates of analysis (CoA), or compatibility with specific synthetic protocols, please reach out to Aladdin Scientific's technical support team. Expedited shipping options and international delivery are available; consult the shipping and delivery policy for current lead times and carrier options.

Frequently asked questions

What is 2,4,4,5,5-Pentamethyl-1,3,2-dioxaborolane used for in organic synthesis?

This compound functions as a cyclic boronic ester reagent in organoboron chemistry, serving as a boron-transfer agent in transesterification reactions, as a building block for more complex boronate esters, and as a reference or intermediate in reactions such as Suzuki–Miyaura cross-coupling. Its steric profile from five methyl substituents influences selectivity in hydroboration-related applications.

How should 2,4,4,5,5-Pentamethyl-1,3,2-dioxaborolane be stored to maintain its stability?

The reagent should be stored in a tightly sealed container under an inert atmosphere (nitrogen or argon) at reduced temperature, away from moisture, light, and heat. Cyclic boronic esters can undergo hydrolysis upon prolonged exposure to water or humid air, releasing boric acid and the corresponding diol, so moisture exclusion is critical for maintaining reagent quality.

What is the difference between 2,4,4,5,5-Pentamethyl-1,3,2-dioxaborolane and pinacolborane (HBpin)?

Pinacolborane (HBpin) is a boron–hydrogen compound (B–H reagent) bearing a pinacol-derived dioxaborolane ring, actively used as a hydroborating agent due to its reactive B–H bond. 2,4,4,5,5-Pentamethyl-1,3,2-dioxaborolane, by contrast, is a boronic ester without a B–H bond, making it more relevant as a boron-protecting group, transesterification partner, or synthetic building block rather than a direct hydroboration reagent. Researchers should select the appropriate reagent based on the specific transformation required.

Is 2,4,4,5,5-Pentamethyl-1,3,2-dioxaborolane air- and moisture-sensitive?

Like most boronic esters, this compound has some sensitivity to moisture because the B–O ester bonds can hydrolyze under aqueous or humid conditions. Handling under inert gas with standard Schlenk or glovebox techniques is advisable for prolonged or large-scale use. For short-term bench operations, minimizing exposure time to air and using dry solvents is typically sufficient.

Where can I find the Certificate of Analysis (CoA) and Safety Data Sheet (SDS) for P404927?

Certificates of Analysis and Safety Data Sheets for Aladdin Scientific product P404927 are available on the Aladdin Scientific website product page. You can also contact Aladdin Scientific customer service or technical support to request lot-specific documentation. Always consult the SDS before first use to understand hazard classifications and proper handling procedures.

References

1. TCI Chemicals Product Catalogue, P2602: 2,4,4,5,5-Pentamethyl-1,3,2-dioxaborolane. Tokyo Chemical Industry Co., Ltd.
2. Hall, D. G. (Ed.) Boronic Acids: Preparation and Applications in Organic Synthesis, Medicine and Materials. Wiley-VCH, 2011.
3. Miyaura, N.; Suzuki, A. Palladium-Catalyzed Cross-Coupling Reactions of Organoboron Compounds. Chemical Reviews 1995, 95 (7), 2457–2483. doi:10.1021/cr00039a007
4. Brown, H. C.; Singaram, B. Development of a Simple Procedure for the Synthesis of Pure Enantiomers via Chiral Organoboranes. Accounts of Chemical Research 1988, 21 (8), 287–293. doi:10.1021/ar00152a003

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