Water-soluble Pd catalysts

Addition to multiple bonds. A water-soluble Pd catalyst (picolinic acid as one of the ligands) is applicable to the synthesis of 2-arylpropanoic acids from styrenes by carbonylation. ... 

In hydrocarboxylation reactions, hydride intermediates are involved, and mechanisms similar to that of Figure 4.6 operate. In the hydrocarboxylation of ethylene to propionic acid (reaction 4.6.1) using a water-soluble Pd catalyst, the involvement of a hydride intermediate has been observed by NMR. 

Bayer (1997) has claimed that in a water-CH2Cl2 system, using water soluble Pd(OAc)2 -triphenylphosphine trisulphonic acid catalyst, octa-2,7-dienyl-l-amine and octa 1,7-dienyl -3-amine can be obtained by telomerization of butadiene with ammonia. 

Amatore et al. developed an aqueous cross-coupling reaction of terminal alkynes with 1-iodoalkynes using a water-soluble Pd(0) catalyst prepared in situ from Pd(OAc)2 and sulfonated triphenylphosphine P(C6H4 — m-SCENa (TPPTS) without Cu(I) promoter, giving diynes with moderate yields (43-65%)(Eq. 4.22) 42... 

Recently, great advancement has been made in the use of air and oxygen as the oxidant for the oxidation of alcohols in aqueous media. Both transition-metal catalysts and organocatalysts have been developed. Complexes of various transition-metals such as cobalt,31 copper [Cu(I) and Cu(II)],32 Fe(III),33 Co/Mn/Br-system,34 Ru(III and IV),35 and V0P04 2H20,36 have been used to catalyze aerobic oxidations of alcohols. Cu(I) complex-based catalytic aerobic oxidations provide a model of copper(I)-containing oxidase in nature.37 Palladium complexes such as water-soluble Pd-bathophenanthroline are selective catalysts for aerobic oxidation of a wide range of alcohols to aldehydes, ketones, and carboxylic acids in a biphasic... 

A prime advantage of such biphasic systems is that the catalyst resides in one phase and the starting materials and products are in the second phase, thus providing for easy recovery and recycling of the catalyst by simple phase separation. A pertinent example is the aerobic oxidation of alcohols catalyzed by a water-soluble Pd-bathophenanthroline complex (Figure 9.5). The only solvent used is water, the oxidant is air, and the catalyst is recycled by phase separation. 

Unmodified poly(ethyleneimine) and poly(vinylpyrrolidinone) have also been used as polymeric ligands for complex formation with Rh(in), Pd(II), Ni(II), Pt(II) etc. aqueous solutions of these complexes catalyzed the hydrogenation of olefins, carbonyls, nitriles, aromatics etc. [94]. The products were separated by ultrafiltration while the water-soluble macromolecular catalysts were retained in the hydrogenation reactor. However, it is very likely, that during the preactivation with H2, nanosize metal particles were formed and the polymer-stabilized metal colloids [64,96] acted as catalysts in the hydrogenation of unsaturated substrates. 

Reactions of the same substrate with several nucleophiles were also catalyzed by the water-soluble Pd-complex of a phosphinite-oxazoline ligand which was prepared from natural D-glucosamine (Scheme 6.23) [53]. The catalyst dissolves weU both in water and in CH3CN but not in diethyl ether. Therefore the reactions could be ran either in water/toluene biphasic systems or in homogeneous water/CHaCN solutions. In the latter case, phase separation could be induced by addition of diethyl ether upon which the catalyst moved quantitatively to the aqueous phase. The product was obtained from the organic phase by evaporation of the solvent(s) and the aqueous solution of the Pd-complex was recycled. In aqueous systems the... 

The intramolecular version of Heck-type couplings was investigated for the first time in water, which led to a dramatic change in regioselectivity (118). With water-soluble Pd/tppts catalysts, the generally observed exo... 

Aqueous biphasic catalysis is also used in homogeneous hydrogenations.117-119 In new examples Ru clusters with the widely used TPPTN [tris(3-sulfonatophenyl) phosphine] ligand120 and Rh complexes with novel carboxylated phosphines121 were applied in alkene hydrogenation, whereas Ru catalysts were used in the hydro-genation of aromatics. Aerobic oxidation of terminal alkenes to methyl ketones was carried out in a biphasic liquid-liquid system by stable, recyclable, water-soluble Pd(II) complexes with sulfonated bidentate diamine ligands.124... 

Genet and co-workers devised a water soluble Pd(0) catalyst, [prepared in situ from palladium(II) acetate and trisodium 3,3, 3 -phosphinetriyltribenzenesulfo-nate (TPPTS)] that can be used to deprotect base sensitive penem allyl ester... 

The cross-coupling reactions of various aryl halides and triflates with vinyl- or arylboronic acids and esters (Suzuki cross-coupling reaction) was also carried out in water in the presence of tetrabutylammonium bromide and a base such as Na2C03, using a phosphine-free palladium catalyst to give biaryl derivatives [Eq. 18)1 [108,109]. More recently, Casalnuovo [101] and Gen t [102,110] have performed this reaction using water-soluble palladium catalysts PdCla (tppms)2 and Pd(OAc)2/tppts in water/acetonitrile. 

Jiang and Sen, in a paper on water-soluble Pd(III) catalysts and their use in manufacturing CO/ethylene copolymers wrote [4] ... 

A NEW AND PRACTICAL REMOVAL OF ALLYL AND ALLYLOXY CARBONYL GROUPS PROMOTED BY WATER-SOLUBLE Pd(0) CATALYSTS... 

A new, water soluble palladium catalyst was used in the Sonogashira reaction (Pd(OAc)2 triphenylphosphine-trisulfonate sodium salt) [131], and several groups adapted the Sonogashira coupling and subsequent cyclization to the solid-phase synthesis of indoles. Bedeschi and coworkers used this method to prepare a series of 2-substituted-5-indolecarboxylic acids [132], CoUini and Ellingboe extended the technique to l,2,3-trisubstituted-6-indolecarboxylic acids [133]. Zhang and... 

On the bases of the Pd-catalyzed carbonylation of benzylic halides Sheldon et al. investigated the functionalization of 5-hydroxymethylfurfural to 5-formylfuran 2-acetic acid in an aqueous medium in the presence of a water-soluble Pd/TPPTS catalyst (Scheme 3) [4]. They found that the hydroxy group displays similar reactivity under acidic conditions as the benzylic halides. 

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