Cross-coupling reactions Glaser reaction

Some of the most useful synthetic transformations of terminal alkynes involve intermolecular and intramolecular homo- and cross-coupling reactions between their. sp-carbon centers, leading to butadiyne or polyyne derivatives. The two most widely used and practical systems are (i) oxidative homocoupling reactions, i.e. Glaser and Eglington reactions and (ii) heterocoupling reactions, i.e. Chodkiewicz-Cadiot coupling of a terminal alkyne with a haloalkyne. 

Cross-coupling reactions were carried out in direct aqueous miniemulsions with 1,2,4-tribromobenzene as crosslinker, and Pd as catalyst [147], in order to obtain aqueous latexes of crosslinked poly(p-phenylene ethynylene) with good optoelectronic properties. The Glaser couphng reaction was also used to synthesize fluorescent conjugated particles of poly(arylene diethynylenes) in direct miniemulsions [148]. For this, 4,4 -dinonyl-2,2 -bipyridine was found to be a suitable ligand for solubilizing the copper (I) chloride catalyst in the toluene droplets. In this case, a solution of the monomers in toluene was first mixed with the solution of the catalyst, and the resultant mixture then miniemulsified in an aqueous solution of cationic surfactant. 

Recent advances in the chemistry of metal-containing knots include the preparation of composite and heteronuclear knots. The composite knots are based on copper templates and phenanthroline ligating moieties, this time linked by alkynic coupling (Glaser) reactions. Despite their complexity, with a minimum of six crossing points in planar representation (Figure 4-28), these species have been fully... 

The Castro-Stephens reaction is the cross coupling of a copper acetylide (1) and an aryl or vinyl halide (2) to give a disubstituted alkyne (3). The reaction, which shares some common elements with the Sonogashira, Cadiot-Chodkiewicz, Rosenmund-von Braun, Hay, and Glaser coupling reactions, was discovered by Stephens and Castro in the early 1960s and has found some applications in synthesis. " ... 

---