SYNTHESIS OF ASYMMETRIC SECONDARY PHOSPHINES BY THE CROSS COUPLING OFARYL HALIDES WITH SILYLPHOSPHINES

The cross coupling of aryl halides with alkyl(trimethylsilyl)phosphine s catalyzed by zero-valent palladium complexes yields secondary alkyla rylphosphoranes containing both electron-donor and electron-withdrawin g substituents in the aromatic ring. The reversible disproportionation of alkylsilylphosphines to give AlkPH2 and AlkP(SiMe3)2 was observed for the first time during this reaction. This disproportionation does not affect the yield of AlkArPH, which are formed in virtually quantit ative yield, due to the high rate of cross coupling with AlkP(SiMe3)H2 and the reversibility of the disproportionation process.