Studies on the heavy chalcogen atom effect on phenochalcogenazines

In the context of cross-dehydrogenative C–N bond formations, phenothiazine has taken a special role. It was found that the click-like amination of phenols can be realized using any oxidant without the use of catalysts. However, when exchanging the sulfur bridging atom by e.g. carbon or nitrogen or using diaryl amines the reaction does not work. In the course of this work the sulfur backbone was exchanged by the heavier chalcogens, selenium and tellurium. The reactivity of phenoselenazine and phenotellurazine was studied compared to phenothiazine. Moreover, phenotellurazine was found to be an efficient redox catalyst enabling oxidative coupling reaction in the presence of molecular oxygen.