Carbon Sonogashira coupling

Carbon-carbon bond formation reactions and the CH activation of methane are another example where NHC complexes have been used successfully in catalytic applications. Palladium-catalysed reactions include Heck-type reactions, especially the Mizoroki-Heck reaction itself [171-175], and various cross-coupling reactions [176-182]. They have also been found useful for related reactions like the Sonogashira coupling [183-185] or the Buchwald-Hartwig amination [186-189]. The reactions are similar concerning the first step of the catalytic cycle, the oxidative addition of aryl halides to palladium(O) species. This is facilitated by electron-donating substituents and therefore the development of highly active catalysts has focussed on NHC complexes. 

Other successful examples of catalysts containing NHC ligands are found in palladium- and nickel-catalyzed carbon-carbon bond formations. The catalyst development with these metals has focused in particular on Heck-type reactions, especially the Mizoroki-Heck reaction itself [Eq. (42)] and various cross coupling reactions [Eq. (43)], e.g., the Suzuki-Miyaura reaction ([M] = and the Kumada-Corriu reaction ([M] = MgBr). " Related reactions like the Sonogashira coupling [Eq. (44)]326-329 Buchwald-... 

Alkynyltin reagents applications, 9, 360 in Sonogashira coupling, 11, 18 in i/ -hydridized carbon polymerization, 11, 674-675 Alkynyltriphenylbismuthonium salts, in G—heteroatom bond formation, 9, 450... 

Sonogashira coupling can be elegantly and efficiently carried out copper-free [17], Similarly to sp -carbon halides, activated olefins can be linked with terminal alkynes [18]. 

Lowary, Bock, and coworkers have prepared carbon-linked glycopeptides, such as 216, via Sonogashira coupling of glycosyl acetylene 214 and aromatic iodide 215 (Scheme 41) [61]. 

The Sonogashira coupling of 2,4-dichloroquinoline in water with a palladium-carbon catalyst (triphenylphosphine, triethylamine, Cul, 80 °C) shows complete selectivity for the 2-position and Suzuki couplings of 1,3-dichloroisoquinoline are selective for C-1. ... 

The Sonogashira coupling reaction of terminal alkynes with aryl or vinyl halides is a useful tool for carbon—carbon bond formation, and has found wide employment in areas such as natural product synthesis, the pharmaceutical industry, and material sciences. Novel recyclable Pd catalysts with fluorous ponytails in the ligand 2,2 -bipyridine were reported in a copper-free Pd-catalyzed Sonogashira reaction in a fluorous biphasic system (FBS) (Equation 4.19). The catalysts are only soluble in perfluorinated solvents at room temperature [41],... 

Other biphasic C—C bonding reactions were carried out with fluorous solvents, for instance Suzuki- and Sonogashira-couplings [124] or ethene or propene oligomerizations [125, 126], Further new solvent systems use ionic liquids for the linear dimerisation of 1-butene to octenes [127] or the hydrovinylation of styrene with a combination ionic liquid/supercritical carbon dioxide [128] (cf. Section 7.4). 

Scheme 164. Carbon-Heteroatom Bond Formation by (a) Coupling with a Heteroatom, (b) Amino-Heck Reaction, (c) Insertion of C-C Unsaturated Bonds-Coupling with Heteroatoms, and (d) Sonogashira Coupling of Terminal Alkynes Followed by Cyclization...

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