Reversible addition-fragmentation chain transfer (RAFT) polymerization has been used to prepare alkane-soluble poly(4-alkylstyrene)-bound organocatalysts and hindered phosphine ligands. Both tert-butylstyrene and 4-dodecylstyrene were copolymerized with 5-10 mol% of 4-chloromethylstyrene using conventional or RAFT chemistry to afford poly(tert-butylstyrene-co-4-dodecylstyrene-co-vinylbenzyl chloride) polymers that undergo substitution of the benzylic chlorine. For example, substitution with a dicyclohexylphosphinobiphenyl ligand yields an electron-rich air stable pendant phosphine ligand. Palladium complexes of this poly(4-alkylstyrene)-bound phosphine were compared to those formed with a polyisobutylene (PIB), whose terminus was also converted into a dicyclohexylphosphinobiphenyl ligand. Both complexes were active and recyclable catalysts in haloarene-amine and haloarene-arylboronic acid couplings. Additionally, a diphenylstyrylphosphine ligand was incorporated onto the poly(tert-butylstyrene-co-4-dodecylstyrene) polymer via RAFT chemistry. The catalytic activity of these polymer-supported phosphine ligands and their recycling will be discussed and compared with similar recovery/reuse of poly(4-alkylstyrene)-bound organocatalysts.

Soluble polymer supported reusable organo- and palladium-based catalyst for acylation, aryl amination, and cross-coupling chemistry

246th National Meeting (2013)

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