Methyl 3-methoxy-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzoate

This substance is commonly supplied as a viscous yellow oil or low-melting solid at ambient temperature -2. Its molecular formula is C15H21BO5 with a formula weight of 292.14 -1-4. The predicted boiling point is approximately 401 °C at 760 Torr, and the estimated density is 1.11±0.1 g/cm³ at 20 °C -2. It is soluble in common organic solvents such as tetrahydrofuran, dichloromethane, and dimethyl sulfoxide, while showing negligible solubility in water. The pinacol boronate ester moiety is prone to gradual hydrolysis upon exposure to atmospheric moisture; therefore, storage in a tightly sealed container under refrigeration (2–8 °C) in a dry environment is essential to maintain stability -2-5. The compound carries GHS hazard classifications with signal word "Warning" and is associated with statements indicating harm if swallowed, in contact with skin, or if inhaled (H302+H312+H332) -6.

Methyl 3-methoxy-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzoate is a bifunctional aromatic building block featuring a benzoate ester core substituted with a methoxy group and a pinacol-protected boronic acid. The boron handle is positioned ortho to the methoxy substituent, creating a substitution pattern that influences both electronic distribution and steric accessibility. The pinacol ester serves as a latent cross-coupling partner, shielding the boronic acid from premature oxidation while remaining readily activated under palladium catalysis. The methyl ester provides a second orthogonal functional group that can be unmasked to reveal the carboxylic acid for amide formation or further derivatization. The calculated physicochemical parameters include a topological polar surface area of 53.99 Ų, moderate lipophilicity with consensus LogP near 1.52, and favorable solubility characteristics for drug-like molecules -1. This compact, densely functionalized arene serves as a versatile intermediate for constructing more complex architectures where precise introduction of both boronate and ester functionalities is required.

Suzuki-Miyaura Cross-Coupling Applications
This boronate ester is primarily employed as a coupling partner in palladiumcatalyzed Suzuki-Miyaura reactions with aryl and heteroaryl halides -3-8-10. The boron moiety facilitates transfer of the substituted benzoate fragment to electrophilic partners, enabling construction of biaryl systems prevalent in pharmaceutical intermediates and agrochemicals. Typical reaction conditions utilize palladium catalysts such as Pd(PPh3)4 or Pd(OAc)2 with bases including potassium carbonate or sodium hydroxide in solvents like tetrahydrofuran or dimethylformamide -3-8. The resulting coupled products retain the methyl ester for subsequent elaboration.

Pharmaceutical Intermediate Synthesis
In medicinal chemistry programs, this compound serves as a precursor for assembling biologically active molecules containing the 3-methoxybenzoate motif -1-10. The ester group can be hydrolyzed to reveal the carboxylic acid for amide coupling with amine-containing pharmacophores, while the boronate handle enables late-stage diversification through cross-coupling. Its structural features make it valuable for constructing kinase inhibitors and receptor modulators where the methoxybenzoate fragment contributes to target engagement and metabolic stability.

Materials Science and Polymer Chemistry
The rigid aromatic core and orthogonal functional groups make this compound suitable for incorporation into functional polymers and covalent organic frameworks. Through cross-coupling polymerization, it can serve as a monomer for constructing conjugated materials with tailored optoelectronic properties. The boronate ester also enables surface immobilization on diol-functionalized substrates, supporting development of sensing platforms and hybrid materials where precise placement of the benzoate moiety influences material characteristics.

Organic Synthesis Building Block
As a versatile synthetic intermediate, this compound participates in diverse transformations beyond standard cross-coupling -3-8. The boronate group engages in Chan–Lam aminations, oxidative Heck reactions, and conjugate additions, while the methyl ester can be reduced to the corresponding alcohol or converted to other functional groups. The ortho relationship between methoxy and boronate enables studies in directed metalation and sequential functionalization, providing access to polysubstituted arenes for natural product synthesis and methodology development.