Azide- and Fluorine-Containing Polystyrenes as Potential Phosphine Sponges Based upon Staudinger Reactions: Application to the Phase Transfer Activation of Grubbs' Catalyst

There are numerous potential applications of phosphine sponges, but optimal systems are yet to emerge. Toward this end, Staudinger reactions of a known polymer derived by substituting the p-fluorine atoms in poly(2,3,4,5,6-pentafluorostyrene) by azide and a new copolymer based upon styrene and p-(methylamino)styrene in which the CH2NH2 linkages have been converted to p-N3C6F4C(=O)NH moieties (PSXArF4N3) have been investigated. They efficiently react with PCy3, PPh3, and P(OEt)(3) to give new polymers with C6F4N=PX3 linkages. These are characterized, among other techniques, by IR spectroscopy, including N-15 labeling. Olefin metatheses with Grubbs' catalyst, (Cl)(2)Ru(PCy3)(2)(=CHPh), require an initial PCy3 dissociation step, but its reversibility can retard reactions. Accordingly, rates are accelerated when ring closing metatheses are conducted in the presence of solid PSXArF4N3 in THF, a phenomenon termed (liquid/solid) phase transfer activation.

Automated summary

Phosphine sponges have numerous potential applications, but optimal systems have not yet been identified. The reactions of a known polymer and a new copolymer with various reagents were investigated, revealing a phenomenon called phase transfer activation.