Copper catalysts, cross couphng

Route 1 involves an initial migratory arylzincation pathtvay that is followed by a copper-mediated reaction with elemental sulfur, with accompanying C-S cyclization to afford a substituted benzothiophene in a one-pot reaction. Alternatively, in route 2, the zinc intermediate is first trapped by iodine, and subsequent copper-catalyst allows C-S/C-Se bond formation followed by cyclization in the presence of elemental sulfur or selenium to afford the corresponding benzochalcogenophene. A modular two-step synthesis of dithieno[3,2-l) 2, 3 -d]thiophene derivatives by C-S cross-coupling and oxidative dehydro C-H coupHng was also described in the year 2014 (14OL4086). 

Miura, M., Tsuda, T., Satah, T. et al. (1998) Oxidative cross-couphng of N- 2 -phenylphenyl)benzenesulfonamides or benzoic and naphthoic acids with alkenes using a paUadium-copper catalyst system under air. J. Org. Chem., 63, 5211-5. 

Islam, S. M., Mondal, S., Mondal, R, Roy, A. S., Tuhina, K., Salam, N., and Mobarak, M. 2012. A rensable polymer supported copper catalyst for the C-N and C—O bond cross-couphng reaction of aryl halides as well as arylboronic acids. J. Organometal. Chem. 696(26) 4264-4274. 

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. 

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