Glaser oxidative coupling

Macrocycle synthesis based on oxidative Glaser coupling suffers from the same handicap [20, 21] For example, Tobe s group investigated the synthesis and properties of diethynylbenzene macrocycles in great detail [22], The dimer unit 45 is ac-... 

The Glaser coupling reaction is carried out in aqueous ammonia or an alcohol/ammonia solution in the presence of catalytic amounts of a copper-I salt. The required copper-II species for reaction with the acetylide anion R-C=C are generated by reaction with an oxidant—usually molecular oxygen. For the Eglinton procedure, equimolar amounts of a copper-II salt are used in the presence of pyridine as base. 

The alcohol 172 obtained by reaction of 86 with ethynyl magnesium bromide on oxidation with manganese dioxide gave the ketone 17361 Glaser coupling of the ketone 173 gave an equimolar mixture of the two acyclic diketones 170 and 174. 

Oxidative homo-coupling of terminal alkynes mediated by stoichiometric (or often excess) Cu(OAc)2. A variant of the Glaser coupling reaction. 

It must be emphasized that current mechanistic understanding of copper-mediated oxidative acetylenic couplings is unsatisfactory. Several studies have shown the strong dependency of the mechanism on the experimental setup, suggesting highly complex coherences and interactions. Nevertheless, the mechanistic idea of Bohlmann et al. described above still provides the most accepted picture for Glaser-type oxidative acetylenic homocouplings. 

The synthesis of conjugated diynes via the Glaser coupling reaction " is the classical method for homocoupling of terminal alkynes. The coupling reaction is catalyzed by CuCl or Cu(OAc)2 in the presence of an oxidant and ammonium chloride or pyridine to yield symmetrically substituted diynes. " The oxidative dimerization appears to proceed via removal of the acetylenic proton, formation of an alkynyl radical, and its dimerization. 

Cu-catalyzed Glaser coupling Preparation of symmetrical conjugated diynes and polyynes by the oxidative homocoupling of terminal alkynes in the presence of copper salts. 186... 

An intriguing aspect of carbon chemistry is the preparation of infinite one-dimensional rods constituted of alkyne units. Interest in such compounds dates back to Baeyer, who studied the oxidative Glaser [66] coupling of acetylenes in the search for infinite linear chains of pure carbon [67]. A century later, the preparation and characterization of infinite linear polyynes [-(CsQ -] named carbynes were actively pursued using a variety of methods [68], But reports of the preparation and structure of these materials, which are calculated to be onedimensional conductors, remain controversial [69]. 

Sometimes known as the Glaser-Hay coupling, it is the oxidative homo-coupling of terminal alkynes using copper catalyst in the presence of oxygen. 

Our interest in building enzyme mimics based on porphyrins led us to synthesise cyclic porphyrin oligomers using Glaser coupling.[9] This reaction oxidatively combines two terminal acetylenes to give a butadiyne link ... 

---