In separate experimens the quantity of Cu which was "washed out" from the composites to the solution was analyzed. In the case of Cu@SiO2-19, the reaction mixture initially contained 11.9 % of Cu as solid in the composite; after completion of the reaction Cu content in solution was 3.1 % (relative to initial quantity of 1). In this case, high yield of 3 could be acieved due to dissolved Cu, because addition of 2.5 % of Cu allowed to reach even higher yield (Fig. ). Situation was completely different for the cases of low Cu loading. Washing out of the same fraction of Cu could not ensure high yield of 3, if only dissolved Cu was active (Fig. ). Such analysis gives evidences for the catalytic action of Cu in solid phase, however contribution of the dissolved Cu can't be excluded. the yields, reached in similar conditions using CuCl2 as soluble catalyst. These lines were plotted using data published in previous article .