Synthesis and characterisation of novel o-xylene-based P,E ligands

Abstract

A range of novel hybrid ligands of the type, o-C₆H₄(CH₂PBu^t₂)(CH₂E) (E = P(C₆F₅)₂, SBu^t, SPh, S(O)Bu^t, NR₂, SiPh₂H), have been synthesised in two or three steps from the common substrate, o-C₆H₄{CH₂PBu^t₂(BH₃)}(CH₂Cl). The initial step involved treatment of the substrate with the appropriate nucleophilic reagent, or preparation of a Grignard reagent from o-C₆H₄{CH₂PBu^t₂(BH₃)}(CH₂Cl) and reaction with the appropriate electrophile. In most cases, this versatile strategy produced air-stable crystalline ligand precursors. Phosphine deprotection was achieved via one of three methods, dependent upon the properties of the second functional group. An alternative synthesis of the known ligand, o-C₆H₄(CH₂PBu^t₂)(CH₂PPh₂), is also presented.