RuPhos

Technical Specifications

Product Description & Scientific Applications

RuPhos (2-dicyclohexylphosphino-2′,6′-diisopropoxybiphenyl) is a Buchwald dialkylbiaryl monophosphine ligand for palladium-catalysed cross-coupling. The electron-rich dicyclohexylphosphino group sits on a biphenyl backbone carrying 2′,6′-diisopropoxy substituents — the feature that distinguishes RuPhos from its dimethoxy analogue SPhos. It is a single-phosphorus (monodentate) ligand, paired with a palladium source such as Pd(OAc)₂ or Pd₂(dba)₃, and is also supplied as air-stable palladium precatalysts (the RuPhos Pd G1–G4 series) that generate the active catalyst reproducibly without a glovebox.

Mechanistic basis. Strong σ-donation from the dialkylphosphine combined with the steric bulk of the biaryl scaffold generates a highly active, low-coordinate LPd(0) species. The electron density accelerates oxidative addition into strong C–X bonds, bringing aryl chlorides and other less reactive electrophiles into range; the bulk favours the monoligated palladium centre and assists reductive elimination of the product. RuPhos-based catalysts have been shown to form the active monoligated Pd(0) complex quantitatively under the reaction conditions.

Applications and Reactions

• Negishi coupling. The catalyst on which RuPhos was introduced: with a palladium source it couples organozinc reagents with aryl halides, enabling efficient synthesis of hindered tri- and tetra-ortho-substituted biaryls at low catalyst loadings, with broad functional-group tolerance and compatibility with heterocyclic substrates.
• Buchwald–Hartwig amination. One of two ligands (with BrettPhos) that together cover most palladium-catalysed C–N couplings: RuPhos is the ligand of choice for secondary amines, coupling functionalised aryl and heteroaryl halides at low loadings and short reaction times in robust, glovebox-free reactions.
• Suzuki–Miyaura coupling. Forms C–C bonds between boron nucleophiles and aryl or heteroaryl chlorides; in the coupling of potassium alkyltrifluoroborates with aryl and heteroaryl chlorides, RuPhos ranked among the most effective ligands examined.
• Palladium precatalysts. Supplied as the RuPhos Pd G1–G4 precatalysts, which deliver a defined 1:1 ligand-to-palladium ratio and generate the active species rapidly and reproducibly for coupling and screening work.

Further reading: For phosphine-ligand selection, palladium sources and precatalysts, and Suzuki–Miyaura and Buchwald–Hartwig reagent choice, see NorrChemica's Lab Journal guide: Phosphine Ligands for Cross-Coupling.

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