3,5-Bis(trifluoromethyl)phenylboronic Acid

Technical Specifications

Product Description & Scientific Applications

3,5-Bis(trifluoromethyl)phenylboronic acid (3,5-bis(trifluoromethyl)benzeneboronic acid) is a strongly electron-poor arylboronic acid. Two trifluoromethyl groups occupy the 3- and 5-positions, meta to boron; both withdraw electron density by induction and raise the acidity of the boronic acid relative to the unsubstituted parent. The symmetric substitution makes the six fluorines equivalent, giving a single 19F resonance as a clean spectroscopic handle. Like the meta- and para-trifluoromethyl isomers, it resists protodeboronation, and couples reliably under aqueous conditions. It is used as a 3,5-bis(trifluoromethyl)phenyl building block in medicinal chemistry, agrochemicals, and electron-poor π-conjugated materials.

May contain small amounts of the cyclic anhydride 3,5-bis(trifluoromethyl)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: with aryl, heteroaryl, or alkenyl electrophiles to give 3,5-bis(trifluoromethyl)-substituted biaryls, heterobiaryls, and styrenes under matched Pd/base conditions.
• Rhodium-catalysed conjugate addition: aryl donor in asymmetric 1,4-addition to enones, nitroalkenes, and related acceptors, installing the electron-poor aryl group with enantiocontrol under a chiral ligand.
• Chan–Lam coupling: copper-mediated C–N and C–O arylation onto amines, amides, sulfonamides, and phenols. As a strongly electron-poor arene, it couples in lower yield and over longer reaction times than electron-neutral or electron-rich boronic acids.
• Nickel-catalysed aryl transfer to aldehydes: 1,2-addition to aryl aldehydes to give electron-poor diarylmethanols.
• 19F NMR handle: the six equivalent fluorines give a single sharp 19F signal, a sensitive reporter for tracking the aryl group in reactions, binding studies, and complex mixtures.
• Electron-poor materials building block: Suzuki installation of the 3,5-bis(trifluoromethyl)phenyl unit into biaryls, chromophores, ligands, and organic-electronic architectures as an electron-accepting group.
• Non-classical arylation: with arenediazonium salts, diaryliodonium salts, and related hypervalent-iodine reagents.
• Protected boronate esters: precursor to pinacol (Bpin), neopentyl glycol, and MIDA boronates for iterative cross-coupling.
• Ipso-halodeboronation: conversion of the C–B bond to C–Br, C–Cl, or C–I under electrophilic halogenation.
• Oxidative hydroxylation: to 3,5-bis(trifluoromethyl)phenol under peroxide, photoredox, or copper-catalysed conditions.

Further Reading

For boronic acids, boronic esters, organotrifluoroborates, 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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