4-(Hydroxymethyl)phenylboronic Acid

Technical Specifications

Product Description & Scientific Applications

4-(Hydroxymethyl)phenylboronic Acid (4-Hydroxymethylbenzeneboronic Acid, 4-Boronobenzyl Alcohol) is a bifunctional arylboronic acid building block (combining arylboronic-acid and alcohol-derived reactivity).

The product may contain small amounts of the cyclic anhydride 4-(hydroxymethyl)phenylboroxine; under aqueous or basic coupling conditions the two forms re-equilibrate and the impact on yield is minor.

Applications and Reactions

• Suzuki–Miyaura coupling: couples with aryl, heteroaryl, and alkenyl halides or triflates under standard Pd-catalysed aqueous-basic conditions to give biaryl, heterobiaryl, and styrene-type products; the para-benzylic alcohol is typically retained as a post-coupling functional handle.
• Bifunctional handle for multistep synthesis (MIDA platform): this compound is a model substrate of the MIDA-boronate diversification platform. As its MIDA boronate, the benzylic hydroxyl is oxidised cleanly under Swern, PDC, TPAP/NMO, Dess-Martin, and even Jones (H2SO4/CrO3, high yield to the benzoic acid) while the C–B bond is preserved, giving direct access to 4-formyl- and 4-carboxy-phenyl MIDA boronates as iterative cross-coupling building blocks.
• Hydroxymethyl handle on the free boronic acid: standard benzylic alcohol chemistry applies — Appel halogenation, mesylation, tosylation, Mitsunobu, etherification, esterification, carbamate formation, controlled oxidation to the aldehyde or acid — within the compatibility limits of any onward steps in the target molecule (the unprotected boronic acid does not survive strongly oxidising conditions such as Jones).
• Reversible boronate ester formation with diols: as an arylboronic acid, forms reversible covalent boronate esters with cis-1,2- and 1,3-diols, saccharides, and catechols in aqueous media. The para-hydroxymethyl group provides an additional alcohol handle for scaffold or surface attachment.
• Dynamic-covalent boronate–diol networks: class-level arylboronic-acid chemistry. The reversible boronate–diol bond underpins self-healing polymers, pH- and glucose-responsive hydrogels, and crosslinked dynamic networks; the bifunctional para-hydroxymethyl architecture provides an additional anchoring site for orthogonal modification.
• NLO-active polyurethane materials: building block in the synthesis of polyurethanes containing spindle-type chromophores for second-order nonlinear optical (NLO) applications.
• Copper-catalysed transformations of arylboronic acids in water: general Cu2O/NH3-in-water method converting arylboronic acids into aryl iodides, azides, sulfones, phenols, anilines, and nitroarenes under air using inexpensive inorganic functional-group sources.
• Chan–Lam-type C–N and C–O coupling: class-level arylboronic-acid chemistry. With Cu(OAc)2 or related Cu(II) systems and an amine, amide, sulfonamide, carbamate, phenol, or selected alcohol partner under mild aerobic conditions, gives the corresponding N-aryl or O-aryl product.
• Petasis borono-Mannich reaction: class-level arylboronic-acid chemistry. The boronic acid acts as the aryl donor in a three-component coupling with an amine and an aldehyde, glyoxylic acid, or α-hydroxy aldehyde partner to give arylated amines, including α-aryl glycine and β-amino alcohol scaffolds.
• Protected boronate derivatives: the corresponding pinacol ester (Bpin) and MIDA boronate are commercially documented. The MIDA derivative is a chromatographically tractable, air-stable boron surrogate compatible with iterative Suzuki coupling under slow-release conditions; the Bpin derivative is a commonly used protected boronate form for handling and cross-coupling workflows. Other boronate forms (neopentyl glycol, Bdan, trifluoroborate, MEA boronate) are class-level options to be selected case by case.
• Non-classical arylation pathways: class-level arylboronic-acid chemistry. Arylboronic acids can participate in Suzuki–Miyaura-type coupling with arenediazonium salts under Pd catalysis, and in base-free Suzuki-type arylation with pentavalent triarylantimony diacetates, providing alternative access to biaryl products outside the usual aryl halide/triflate electrophile set.
• Ipso-halodeboronation: class-level arylboronic-acid chemistry. With NBS, NCS, or NIS, or related halogenating systems, the C–B bond can be converted to C–X to access the corresponding aryl halide; for this substrate, compatible conditions would lead to the 4-halobenzyl alcohol framework.
• Oxidative ipso-hydroxylation: class-level arylboronic-acid chemistry. With H2O2, oxone, sodium perborate, or copper-/photo-mediated aerobic hydroxylation conditions, the C–B bond can be replaced by C–OH to give the corresponding phenol — here, 4-hydroxybenzyl alcohol.

Further Reading

For boronic acids, boronic esters, protodeboronation, boroxine content, and Suzuki–Miyaura reagent selection, see NorrChemica's Lab Journal guide: Choosing Your Boron Source for Suzuki–Miyaura Coupling.

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