copper(ll) bromide in 1,4-dioxane T=80°C; 2 h;

in 1,4-dioxane byproducts: ethyl 3,5-dimethylpyrrole-2-carboxylate; addn. soln. of Tl compound to soln. of Cu(II) compound, stirring (2 h, 80°C); cooling, filtration off inorganic salts, filtrate washing (dioxane), extn. (Et2O), drying (Na2SO4); m. p.;