Pentaphosphaferrocene-mediated synthesis of asymmetric organo-phosphines starting from white phosphorus
Stephan Reichl, Eric Mädl, Felix Riedlberger, Martin Piesch, Gábor Balázs, Michael Seidl, Manfred Scheer
Abstract
Abstract The synthesis of phosphines is based on white phosphorus, which is usually converted to PCl 3 , 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 (P 4 ). Thereby, P 4 is converted to [Cp*Fe(η 5 -P 5 )] ( 1 ) (Cp* = η 5 -C 5 (CH 3 ) 5 ) in which one of the phosphorus atoms is selectively functionalized to the 1,1-diorgano-substituted complex [Cp*Fe(η 4 -P 5 R′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 P 4 and can be reused in multiple reaction cycles without isolation of the intermediates, and only the phosphine is distilled off.