Aqueous media, reactions Heck reaction

Greater durability of the colloidal Pd/C catalysts was also observed in this case. The catalytic activity was found to have declined much less than a conventionally manufactured Pd/C catalyst after recycling both catalysts 25 times under similar conditions. Obviously, the lipophilic (Oct)4NCl surfactant layer prevents the colloid particles from coagulating and being poisoned in the alkaline aqueous reaction medium. Shape-selective hydrocarbon oxidation catalysts have been described, where active Pt colloid particles are present exclusively in the pores of ultramicroscopic tungsten heteropoly compounds [162], Phosphine-free Suzuki and Heck reactions involving iodo-, bromo-or activated chloroatoms were performed catalytically with ammonium salt- or poly(vinylpyrroli-done)-stabilized palladium or palladium nickel colloids (Equation 3.9) [162, 163],... 

Solabannavar, S. B., Desai, U. V., Mane, R. B. Heck reaction in aqueous medium using Amberlite IRA-400 (basic). Green Chem. 2002,4,... 

Jutand, A. Dual role of nucleophiles in palladium-catalyzed Heck, Stille, and Sonogashira reactions. Pure Appl. Chem. 2004, 76, 565-576. Li, C.-J., Slaven, W. T., John, V. T., Banerjee, S. Palladium catalyzed polymerization of aryl diiodides with acetylene gas in aqueous medium a novel synthesis of areneethynylene polymers and oligomers. Chem. Commun. 1997,1569-1570. 

The current method is to perform oxidative cleavage on the corresponding bis-arylacrylic acid sodium salt this requires an additional step involving alkaline hydrolysis of the bis-aryl acrylate and isolation of the salt. Conducting the Heck reaction in an aqueous medium should shorten the route to the target mole-... 

Cross-coupling in homogeneous aqueous medium.1 A catalyst 1 prepared from Pd(OAc)2 and TPPTS (5 1) is soluble in HiO-CH CN or H20-cthanol. It is highly effective in various reactions that have been effected with Pd(OAc)2. It is effective for inter- and intramolecular Heck reactions, for coupling of vinyl or aryl iodides with terminal alkynes, and for allylic substitution. 

For insoluble development in Heck-type reactions is P-C and N-C bond formation, which results from coupling of aryl halides with phosphorous compounds [38] and amines [39]. The first application in aqueous medium was achieved by coupling of a dialkyl phosphite with an aromatic iodide to give an arylphosphonate in 99% yield. In 1996, Stelzer and co-workers presented a P-C cross-coupling reaction between primary and secondary phosphines and functional aryl iodides to water-soluble phosphines [Eq. (9)], which are potentially applicable as ligands in aqueous-phase catalysis [40]. 

Villemin, D. and Nechab, B. (2000) Use of a new hydrophilic phosphine DPPPA. Rapid and convenient Heck reaction in aqueous medium under microwave irradiation. J. Chem. Res. (S), 429-31. 

Lemaire-Audoire, S., Savignac, M., Dupuis, C. and Genet, J.-P. (1996) Intramolecular Heck-type reactions in aqueous medium. Dramatic change in regioselectivity. Tetrahedron Lett., 37, 2003-6. 

Sengupta, S. and Bhattacharya, S. (1993) Heck reaction of arenediazonium salts a palladium-catalyzed reaction in an aqueous medium. J. Chem. Soc., Perkin Trans. 1, 1943-4. 

Heck and Stille coupling reactions, also allowing reactions to be conducted under solvent-free conditions. The synergic effect of polymer 96 and TSIL not only reflected an increased stability during storage but also an enhanced activity during catalysis. Scheme 1.62 shows a typical Suzuki reaction occurring in an aqueous biphasic medium. 

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