Tetrathiafulvalene: a catalyst for sequential radical–polar reactions

The reaction between tetrathiafulvalene (TTF) and suitable arenediazonium salts leads to products arising from an ordered sequence of reactions featuring electron transfer, loss of nitrogen, radical cyclisation and nucleophilic substitution. The tetrathiafulvalenium salt 6 is shown to be an intermediate in the reaction, with substitution of TTF occurring via an SN1 mechanism. The reactions are catalytic in TTF and the final substitution can be achieved by several nucleophiles. Extension of the reaction to the synthesis of bi- and tricyclic ring systems has been investigated.