A new template for the synthesis of triphosphorus macrocycles

Abstract

A new template synthesis of triphosphorus macrocycles has been developed based upon the intramolecular hydrophosphination of allylphosphine coordinated to the (η⁵-cyclopentadienyl)iron(II) cation; the resulting tri-secondary macrocycle 1,5,9-triphosphacyclododecane is readily alkylated with ethene to give (η³-1,5,9-[12]aneP₃Et₃)Fe(η⁵ -Cp)⁺ which is in turn liberated as the free ligand stereospecifically as the syn–syn isomer; related reactions with phenyl(allyl)phosphine lead directly to the triphenyl macrocycle (1,5,9-[12]aneP₃Ph₃) which is also liberated stereospecifically.