Potassium (4-Bromophenyl)trifluoroborate

Technical Specifications

Product Description & Scientific Applications

Potassium (4-bromophenyl)trifluoroborate is an aryltrifluoroborate salt. It is a bench-stable surrogate for 4-bromophenylboronic acid. The boron is four-coordinate, anionic and not Lewis acidic. The reagent is an air- and moisture-stable, ionic crystalline solid.

Suzuki–Miyaura coupling. The boron is a nucleophilic partner in Suzuki–Miyaura cross-coupling. Under aqueous or protic conditions the salt hydrolyses to the boronic acid. The boronic acid transmetalates to palladium. It then couples with an aryl or heteroaryl electrophile.

Bifunctional handle. The ring also carries an aryl carbon–bromine bond. This bond is a reactive cross-coupling electrophile. The trifluoroborate is a robust protected boron group. It tolerates conditions that degrade free boronic acids. The boron and the bromide are orthogonal handles. Their combination supports sequential functionalisation toward terphenyls and extended biaryls.

Further applications

• C–H arylation. Aryltrifluoroborates arylate arene C–H bonds without a prehalogenated partner. Indoles couple at C2 to give 2-arylindoles. A copper oxidant turns over the catalyst.
• Oxidative Heck. The salt arylates alkenes to give arylated alkenes. Acrylates give cinnamates. p-Benzoquinone reoxidises the catalyst.
• Rhodium conjugate addition. Potassium organotrifluoroborates add 1,4 to enones under rhodium catalysis. Asymmetric variants proceed at room temperature.
• Ketone synthesis. They couple with aromatic aldehydes to give ketones. The reaction uses acetone as a hydride acceptor.
• Carbonyl arylation. Aryltrifluoroborates add to aldehydes by 1,2-addition. The reaction gives secondary benzylic alcohols.
• Imine arylation. Potassium organotrifluoroborates add to N-sulfonyl ketimines. Asymmetric variants give chiral amines.
• Petasis amine synthesis. Trifluoroacetic acid promotes addition to imines and enamines. The reaction gives amines with no metal catalyst.
• Chan–Lam coupling. Copper(II) acetate couples aryltrifluoroborates with amines and anilines to give arylamines. It also couples them with alcohols and phenols to give aryl ethers. Oxygen is the oxidant.

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

Shipping Destinations

• EU & UK: Priority delivery, 2–5 business days.
• United States (DDP): 3–7 business days, duties and taxes prepaid.
• EFTA Countries (DDP): 3–7 business days, duties and taxes prepaid.
• Worldwide: 7–14 business days, selected locations.