Pentaphosphaferrocene-mediated synthesis of asymmetric organo-phosphines starting from white phosphorus

The synthesis of phosphines is based on white phosphorus, which is usually converted to PCl₃, to be afterwards substituted step by step in a non-atomic efficient manner. Herein, we describe an alternative efficient transition metal-mediated process to form asymmetrically substituted phosphines directly from white phosphorus (P₄). Thereby, P₄ is converted to [Cp*Fe(η⁵-P₅)] (1) (Cp* = η⁵-C₅(CH₃)₅) in which one of the phosphorus atoms is selectively functionalized to the 1,1-diorgano-substituted complex [Cp*Fe(η⁴-P₅R'R″)] (3). In a subsequent step, the phosphine PR'R″R‴ (R' ≠ R″ ≠ R‴ = alky, aryl) (4) is released by reacting it with a nucleophile R‴M (M = alkali metal) as racemates. The starting material 1 can be regenerated with P₄ and can be reused in multiple reaction cycles without isolation of the intermediates, and only the phosphine is distilled off.