Coupling reactions alkynes

While many examples of alkyne coupling reactions on metal clusters are known, here we are only concerned with those reactions that result in the formation of diyne or diynyl ligands, or the poly-yne/poly-ynyl analogues, by the combination of alkynyl fragments on a cluster core. 

The earliest of the alkyne coupling reactions is that of Glaser, who had noted ... 

These two fragments arc joined with a palladium-catalyzed alkyne coupling reaction. 

A nickel-catalysed alkyne insertion between the carbonyl carbon and the -carbon of the cyclobutanone was achieved by combining a ketone-alkyne coupling reaction with a /3-carbon elimination process (Scheme 79).121 The reaction uses cyclobutanones as a four-carbon unit and provides access to substituted cyclohexenones. 

I. B. Campbell, The Sonogashira Cu-Pd-Catalyzed Alkyne Coupling Reactions, in Organocopper Reagents A Practical Approach (R. J. K. Taylor, Ed.), 217, Oxford University Press, Oxford, U. K., 1994. 

Alkyne coupling reactions under Pd/Cu conditions have been extended to other functional groups. Allenes couple with alkynes without incident (equation 143)277, as do dithio-carbonyl chlorides and thiocarbamoyl chlorides278. Alkynyl chloride cross-couple with alkynes in at least some cases, to form diynes279. 

A tetrahydrofuran fused with a seven-membered ring was obtained from an enyne through a [5+2] cycloaddition reaction catalyzed by [(C10H8)Rh(COD)]+ SbF6 complex <02AG(E)4550>. Rhodium-catalyzed carbonylative alkene-alkyne coupling reactions... 

Bisalkyne derivatives have been crucial to the development of a comprehensive model for n donation in d4 monomers. The presence of two equivalent alkynes in the coordination sphere allows unambiguous interpretation of certain bonding properties, and in particular a formal donor number of three applies for each alkyne (N = 3). Bisalkyne complexes have been exploited to prepare monoalkyne monomers as well as for alkyne coupling reactions and ligand based transformations. 

Fig. 5.4-2. Two types of structures for products of alkyne coupling reactions...

Suzuki imine and an alkyne coupling reactions (1) have been used for preparing diaryl aminoacid Step 1 analogues of the current invention as illustrated in Eq. 1 ... 

It is typically difficult to isolate [Fe(CO)4( -R-CC-R )] complexes (110) without bulky substituents, as they undergo spontaneous alkyne-alkyne coupling reactions, (some of which have tangible synthetic promise). In fact, prior to 1997, only the bistrimethylsilylacetylene complex (110a) had been hilly characterized. However, a number... 

A variation of this aryl-alkyne coupling reaction reacted methylthioalkynes (R—C=C—SMe) with arylboronic acids and a palladium catalyst to give the aryl alkyne (R—C=C—Ar). 1-TrialkyIsilylalkynes (R3Si—C=C—R ) were coupled... 

A number of other C-C bond forming reactions have been described which afford not allenyl but metalloallyl clusters. Carbyne-alkyne coupling reactions are potentially useful as sources of allenyl fragments but... 

Campbell IB (1994) The sonogashira Cu-Pd-catalyzed alkyne coupling reaction. In Organocopper Reagents. Oxford Oxford University Press, 217. 

Reactivity studies reveal that the bis(indenyl)zirconium sandwich complexes serve as isolable, modular precursors to the rich chemistry of divalent zirconocene. Addition of 1 atm of carbon monoxide generates the bis(indenyl)-zirconocene dicarbonyl complex, 307, while treatment with N,N-dimethylaminopyridine results in C-H activation to form the zirconocene pyridyl hydride complex 308. Crystallographic characterization of both complexes as well as multinuclear NMR spectroscopy establishes that the more familiar 77s, 77s hapticity for the indenyl ligands has been restored. Alkyne coupling reactions are also observed as addition of 2-butyne to 302 allows observation of the alkyne complex, 208, and ultimately the zirconacyclopentadiene 309 (Scheme 50).104... 

Azide-alkyne Coupling Reaction by Click Chemistry ... 

In addition, the application of Jeffery s conditions by Sinou and co-workers, with extra triphenylphosphine and tetrabutylammonium hydrogensulfate, confirmed that Cul is not essential to success in alkyne coupling reactions [24], Moreover, they reported the most efficient coupling of bromoanisole with propargyl alcohol in 81% yield. These results prompted the authors to apply these conditions in a cascade reaction, consisting of an intermolecular Heck reaction followed by cyclization of the intermediate cr-complex (Eq. 9). The product, which is a mixture of (E) and (Z) stereomers (approximately 1 1), was sometimes contaminated with a by-product resulting from aromatization, especially for longer reaction times. 

Shibata et al. reported that, in the presence of an iridium catalyst, the carbonylative alkyne—alkyne coupling reaction of the diyne 102 with carbon monoxide gave the tetrahydrofuran-fused cyclopen-tadienone 103 (Scheme 35).114 The rhodium-catalyzed alkyne—alkyne coupling reaction of 102 with the isocyanide 104 produced the iminocyclopentadiene 105 (Scheme 36).114b These reactions proceed through formation of the metallacyclopentadiene intermediate 106, which undergoes insertion either of CO or of the isocyanide 104. 

Coupling is an important reaction of alkynes that leads to di-ynes. It occurs under a variety of condi-tions,32 but is particularly important when alkynylcopper derivatives are involved. Two classical alkyne coupling reactions involve copper derivatives. In the Glaser reaction,33 where an alkyne such as phenylacetylene reacts with basic cupric chloride (CuCl2), subsequent air oxidation gives a diyne (in this case 26 in 90% yield). 

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