XPhos (2-Dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl) | CAS 564483-18-7 | ≥97%

Technical Specifications

Product Description & Scientific Applications

XPhos (2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl; dicyclohexyl[2',4',6'-tris(propan-2-yl)biphenyl-2-yl]phosphane) is a bulky, electron-rich biaryl monophosphine ligand in the dialkylbiaryl phosphine family. It pairs a single dicyclohexylphosphino donor with a 2',4',6'-triisopropylbiphenyl backbone, giving an air-stable crystalline solid that is convenient to weigh and handle. The combination of strong electron donation and large steric bulk promotes highly reactive monoligated palladium species and facilitates oxidative addition of challenging aryl electrophiles.

Buchwald-Hartwig amination of aryl chlorides and tosylates

XPhos-ligated palladium is highly active for carbon–nitrogen cross-coupling, including amination and amidation of aryl chlorides and aryl tosylates. Aryl chlorides are attractive because they are often cheaper and more widely available than the corresponding bromides and iodides, while aryl tosylates provide useful pseudohalide electrophiles derived from phenolic substrates. The bulky, electron-rich ligand assists oxidative addition of these less reactive substrates and is used with amine and amide nucleophiles in Buchwald-Hartwig C–N coupling.

Suzuki-Miyaura, Negishi and Sonogashira coupling

Beyond C–N chemistry, XPhos is an efficient ligand for carbon–carbon bond formation, including Suzuki–Miyaura, Negishi and copper-free Sonogashira coupling. It is effective in the Suzuki–Miyaura coupling of aryl tosylates with boronic acids across a broad range of functional groups and heteroaromatic substrates, and its activity toward aryl chlorides and other demanding electrophiles makes it useful where simpler phosphine ligands give low conversion. Copper-free Sonogashira variants can reduce copper-associated side reactions such as oxidative alkyne homocoupling.

α-Arylation of oxindoles, sulfones and sulfonamides

XPhos-based palladium systems are used in selected α-arylation chemistry, forming carbon–carbon bonds at acidic positions adjacent to carbonyl or strongly electron-withdrawing groups. Documented XPhos examples include C3 arylation of oxindoles with aryl chlorides, bromides and triflates, and Negishi-type α-arylation of sulfones and sulfonamides with aryl bromides. This extends the use of XPhos beyond aryl–aryl cross-coupling into selected C(sp3)–aryl bond-forming reactions.

Monoligated palladium and precatalyst systems

The activity of XPhos is closely tied to formation of monoligated palladium species. Oxidative addition of aryl halides is faster at smaller, more accessible monoligated palladium(0) complexes than at more highly coordinated complexes, and bulky biaryl phosphines help favour this reactive coordination state. XPhos is also incorporated into single-component palladium precatalysts in which an aminobiphenyl palladacycle scaffold generates the monoligated Pd(0)–XPhos species upon activation under basic or reducing conditions.

Handling note

XPhos is an air-stable crystalline solid. For demanding catalytic work, store cool and dry and minimise prolonged air exposure to preserve the trivalent phosphine.

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