Palladium-catalyzed coupling reactions of bromo-substituted phenylphosphine oxides: a facile route to functionalized arylphosphine ligands

The Heck reaction of OPPh3−n(4-C6H4Br)n (n=1–3) with electron deficient and neutral olefins led to linear olefin-substituted phenylphosphine oxides, whilst the reaction with an electron rich olefin in an ionic liquid solvent resulted in the formation of acetyl variants. The same bromophenylphosphine oxides also reacted with arylboronic acids under normal Suzuki coupling conditions, affording arylated phenylphosphine oxides in excellent yields. Amination and methoxycarbonylation of the bromophenylphosphine oxides by palladium catalysis were also shown to be feasible. Given that free phosphines can be readily derived from phosphine oxides, palladium-catalyzed coupling of OPR3−n(C6H4Br)n (R=alkyl, aryl) should provide a simple, yet versatile, route to functionalized phosphine ligands.