Suzuki and Sonogashira Reaction

Corma et al compared the use of different IL solvents and polyethylene glycol (PEG) using a carbopalladacycle complex as catalyst for Suzuki and Sonogashira reactions. They showed that the dialkyl-substituted imidazolium compounds had poor stability, reactivity and recyclability when compared with trialkyl substituted imidazolium compounds and PEG. They concluded that this result could be attributed to the stabilization of the Pd nanoparticles in the solvent. They showed that PEG was a better solvent since it gave better yields, had good stability, low cost and low toxicity. 

Similar selectivities for the first cross-coupling have been observed for Suzuki and Sonogashira reactions. The Stille coupling of 3,4-diiodo-2,5-dimethylthiophene with 2-trimethylstannylthiazole stops at the monosubstitution stage. The reason for this selectivity might be that the carbon at the 3-position retards the oxidative addition and transmetalation at the adjacent 4-position. 

Erdelyi, M., Gogoll, A. Rapid Microwave Promoted Sonogashira Coupling Reactions on Solid Phase. J. Org. Chem. 2003, 68, 6431-6434. Najera, C., Gil-Molto, J., Karlstroem, S., Falvello, L. R. Di-2-pyridylmethylamine-Based Palladium Complexes as New Catalysts for Heck, Suzuki, and Sonogashira Reactions in Organic and Aqueous Solvents. Org. Lett. 2003, 5,1451-1454. 

Polystyrene-supported soluble palladacycle catalyst as recyclable catalyst for Heck, Suzuki and Sonogashira reactions... 

A new type of soluble polystyrene-supported palladium complex was synthesised (Figure 6.1) as an excellent and recyclable palladacycle catalyst for carbon-carbon bond formation in Heck, Suzuki and Sonogashira reactions to give high yields of the desired products. 

The newly invented polystyrene-supported palladacycle catalyst was prepared in six steps with high yields. The simple precipitation and filtration process to recycle the catalyst after model reactions for Heck, Suzuki, and Sonogashira reactions is noteworthy.[1]... 

Methods to form fluorescein and rhodamine dyes typically feature high-temperature condensation reactions that are not readily adapted to form small libraries of derivatives. Burgess and co-workers developed borylation, Suzuki, and Sonogashira reactions involving bromo derivatives of fluorescein and rhodamine [86]. Organoboron compounds, biaryls, and alkynes were readily synthesized by... 

In this chapter, we discuss selected literature on palladium catalysts (or catalyst precursors) for the Heck, Suzuki and Sonogashira reactions. The review covers simple homogeneous palladium complexes, Ugand-free palladium catalytic systems, stable palladium colloids and particles and supported palladium catalysts. It focuses on the role of palladium nanoparticles (as catalyst precursors or formed in situ during the course of the reaction) from a mechanistic point of view. 

The majority of the papers on Suzuki and Sonogashira reactions catalysed by supported palladium do not focus on mechanistic aspects and the corresponding contributions are thus limited in this respect Nevertheless, it is reasonable to assume from the limited number of such investigations that the principal conclusions from detailed mechanistic studies of Heck reactions by supported catalysts are valid also for this group of coupling reactions the active species is Pd leached into solution during the reaction and re-deposited at the end (see next section). 

The corresponding complexes with molybdenum and palladium have been prepared particularly, the Suzuki and Sonogashira reactions have been examined using the protonated form [PhP(GuaH)2, and the results in the latter reaction show better yields than with monosulfonated triphenylphosphine [14]. 

Ndjera, C., Gil-Molt6, J., Karlstrom, S. and Falvello, L.R. (2003) Di-2-pyridylmethylamine-based palladium complexes as new catalysts for Heck, Suzuki, and Sonogashira reactions in organic and aqueous solvents. Org. Lett., 5, 1451-4. 

Some drawbacks of the precursor routes mentioned above have been overcome by the use of polycondensation- and C-C-bond-coupling reactions. To produce soluble PPV-, poly(thiophene)-, or poly(pyrrol) derivatives for spin coating preparation, various types of transition metal catalyzed reactions, such as the Heck-, Suzuki-, and Sonogashira-reaction, Wittig- and Wittig-Horner-type coupling reactions, or the McMurry- and Knoevenagel-condensation have been utilized. 

Three additional processes, the Stille, Suzuki, and Sonogashira reactions, further broaden the scope of transition metal-catalyzed bond-forming processes. All utilize catalytic palladium or nickel the differences lie... 

The ring expansion of oxyglycal-derived gm-dihalo 1,2-cyclopropanate oxyglycals provides stable seven-membered halo-oxepines, that are thus suitable precursors for further functionalizations. In a study, vinyl bromide of the bromo-oxepine was used for the metal-catalyzed cross-coupling reactions, namely, Heck, Suzuki, and Sonogashira reactions, so as to generate 2-deoxy-2-C-alkyl/ary/alkynyl septanosides [33]. 

---