Phosphino-decorated polymer immobilised ionic liquid phase stabilised palladium nanoparticles (PdNP@PPh2-PIILP) and their PEGylated counterparts (PdNP@PPh2-PEGPIILP) are remarkably active and exceptionally selective catalysts for the aqueous phase hydrogenation of α,β-unsaturated aldehydes, ketones, esters and nitriles with PdNP@PPh2-PEGPIILP giving complete conversion and 100% selectivity for reduction of the CC bond, under mild conditions. This is the most selective PdNP-based system to be reported for the aqueous phase hydrogenation of this class of substrates.

Phosphino-decorated polymer immobilised ionic liquid phase stabilised palladium nanoparticles (PdNP@PPh2-PIILP) and their PEGylated counterparts (PdNP@PPh2-PEGPIILP) are remarkably active and exceptionally selective catalysts for the aqueous phase hydrogenation of α,β-unsaturated aldehydes, ketones, esters and nitriles with PdNP@PPh2-PEGPIILP giving complete conversion and 100% selectivity for reduction of the CC bond, under mild conditions. This is the most selective PdNP-based system to be reported for the aqueous phase hydrogenation of this class of substrates.

A homologous series of triaryl-like KITPHOS-type monophosphines containing one, two, or three bulky 12-phenyl-9,10-dihydro-9,10-ethenoanthracene (KITPHOS) units have been developed, and the influence of increasing steric bulk on their efficacy as ligands in gold(I)-catalyzed carbon–heteroatom bond-forming cyclizations has been investigated. Detailed solution NMR studies on Ph-TRISKITPHOS, its oxide, and the corresponding gold(I) chloride adduct identified a conformational exchange process involving a concerted librational motion of the individual anthracene-derived organic substituents about their P–C bonds. The cessation of this motion at reduced temperatures lowers the molecular symmetry such that the two C6H4 rings in each of the KITPHOS units become inequivalent; a lower energy process involving restricted rotation of the biaryl-like phenyl ring has also been identified. Electrophilic gold(I) complexes of these triaryl-like KITPHOS monophosphines catalyze the 5-exo-dig cycloisomerization of propargyl amides to afford the corresponding methylene oxazolines, which were used in a subsequent tandem carbonyl-ene reaction to afford functionalized 2-substituted oxazolines. A comparative survey revealed that catalyst efficiency for cycloisomerization decreases in the order MONOKITPHOS = BISKITPHOS > PPh3 > TRISKITPHOS. The optimum system also catalyzes the selective 6-endo-dig cyclization of 2-alkynylbenzyl alcohols, 2-alkynylbenzoic acid, and 2-phenylethynyl benzamides; gratifyingly, in several cases the yields obtained are markedly higher and/or reaction times significantly shorter than those previously reported for related gold catalysts. Moreover, these are the first examples of gold(I)-catalyzed 6-endo-dig cycloisomerizations involving 2-phenylethynyl benzamides and, reassuringly, the optimum gold(I)/MONOKITPHOS systems either rivaled or outperformed existing silver or palladium-based catalysts. The steric parameters of this homologous series of phosphines have been quantified and compared with selected triarylphosphines using a combination of Solid-G calculations, to determine the percentage of the metal coordination sphere shielded by the phosphine (the G parameter), and Salerno molecular buried volume calculations (SambVca) to determine the percent buried volume (%Vbur); the corresponding Tolman cone angles have also been determined from correlations.

This paper reports the first examples of Suzuki–Miyaura cross-couplings involving aryl- and naphthylphosphonate-based boronate esters as the nucleophilic partner. A systematic comparison of the performance of biaryl-like KITPHOS- and XPHOS-based systems revealed that, between them, an electronically and sterically diverse range of substrates can be coupled with remarkable efficiency to afford high yields of the corresponding biaryl and heterobiaryl monophosphonates. The use of an aryl- and naphthylphosphonate-based boronate ester as the coupling partner presents an alternative and potentially complementary pathway to existing couplings in which the aryl- or naphthylphosphonate unit is typically introduced as the electrophile. The potential advantages associated with the use of this new class of coupling partner were clearly demonstrated by the palladium-catalyzed reaction between diethyl [2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]phosphonate and 1-bromo-2-methoxynaphthalene that gave the corresponding biaryl monophosphonate in 56% yield, a marked improvement on the 6% yield obtained from the reaction between 2-methoxy-1-naphthylboronic acid and diethyl (2-bromophenyl)phosphonate with the same catalyst under the same conditions. The potential utility of this new coupling combination was demonstrated by reducing one of the products, 2-methoxy-1-(2′-diethoxyphosphorylphenyl)naphthylene, to the corresponding primary phosphine, which was subsequently converted into a diastereoisomeric mixture of the R,R-hexane-2,5-diol-derived phospholane in reasonable yield.

Palladium complexes of 2-pyridyldiphenylphosphine anchored on polystyrene, polymethylmethacrylate and styrene–methylmethacrylate copolymer form highly active heterogeneous catalysts for the alkoxycarbonylation of terminal alkynes with activities approaching those obtained under homogeneous conditions.