Coupling reactions Sonogashira

Scheme 21. The Sonogashira coupling reaction in Nicolaou s dynemicin A model study.

We synthesized uniform CU2O coated Cu nanoparticles from the thermal decomposition of copper acetylacetonate, followed by air oxidation. We successfully used these nanoparticles for the catalysts for Ullmann type amination coupling reactions of aryl chlorides. We synthesized core/shell-like Ni/Pd bimetallic nanoparticles from the consecutive thermal decomposition of metal-surfactant complexes. The nanoparticle catalyst was atom-economically applied for various Sonogashira coupling reactions. 

Synthesis of Ni/Pd bimetallic core/shell nanoparticles and their applications to Sonogashira coupling reactions... 

Ni/Pd nanoparticles and similar sized Pd nanoparticles for the following Sonogashira coupling reactions using equal amount of palladium in the reaction mixtures. As expected, the Ni/Pd... 

A copper-free Sonogashira coupling reaction in ionic liquids and its application to a microflow system for efficient catalyst recycling, Org. Lett. 4, 10 (2002) 1691-1694. 

Besides palladium catalysts, nickel was also found to be an effective catalyst for the Sonogashira reaction in aqueous media. Recently, Beletskaya et al. reported a Ni(PPh3)2Cl2/CuI-catalyzed Sonogashira coupling reaction of terminal acetylenes with aryl iodides in aqueous dioxane in high yields (Eq. 4.19).39... 

Dichloro- and 3,5-dibromoisothiazole-4-carbonitriles 285a/b undergo regioselective Stille, Negishi, Sonogashira coupling reactions at C-5 to provide 3-halo-5-substituted... 

A silver(i) complex having the heterosubstituted 3-methyl-l-(2-pyridylmethyl)imidazol-2-ylidene ligand, [Ag(carbene)2] [I/Agl2] 37, was reported, which was further reacted to give a series of palladium(n) carbene complexes that were demonstrated to be active catalysts toward Heck, Suzuki, and Sonogashira coupling reactions.87... 

Scheme 6.52 MW-expedited Sonogashira coupling reaction on palladium-doped alumina.

A rapid MW-assisted palladium-catalyzed coupling of heteroaryl and aryl boronic acids with iodo- and bromo-substituted benzoic acids, anchored on TentaGel has been achieved [174]. An environmentally friendly Suzuki cross-coupling reaction has been developed that uses polyethylene glycol (PEG) as the reaction medium and palladium chloride as a catalyst [175]. A solventless Suzuki coupling has also been reported on palladium-doped alumina in the presence of potassium fluoride as a base [176], This approach has been extended to Sonogashira coupling reaction wherein terminal alkynes couple readily with aryl or alkenyl iodides on palladium-doped alumina in the presence of triphenylphosphine and cuprous iodide (Scheme 6.52) [177]. 

Having pyrazinylacetylenes in hand, one could convert the alkynyne functionality into the corresponding ketone via hydration [33], Thus, the coupling of iodide 36 and acetylene 37 produced pyrazinylalkyne 38. Subsequent exposure of 38 to aqueous sodium sulfide and aqueous hydrochloric acid in methanol led to ketone 39. Such a maneuver provides additional opportunities for further manipulation of the alkynes derived from the Sonogashira coupling reactions. 

Aqueous palladium-catalyzed Sonogashira coupling reactions were also applied for the preparation of polymers (see Chapter 7). 

New macromolecules 99 and 100 can easily be synthesized in four steps from l,2-bis(5-bromo-2-methyl-3-thienyl)perfluorocyclopentene by the Sonogashira coupling reaction (05T12256). 

Scheme 2.21 Copper-catalysed Sonogashira coupling reactions.

Reactions Based on the In Situ Activation of Alkynes by a Sonogashira Coupling Reaction... 

Similar three-component reactions based on in situ activation of alkynes by a Sonogashira coupling reaction have also been developed by Muller and co-workers... 

---