Zsuzsanna Riedl, György Hajós, András Messmer, Antal Rockenbauer, László Korecz, Gert Kollenz, Walter M. F. Fabian, Karl Peters and Eva-Maria Peters
Investigation of reactions of the zwitterionic polycycle 1 with electron-deficient dienophiles revealed that Michael addition products 3 and 4, selective cycloadducts 2 and, in a special case, a stable dimeric radical cation 5 are formed.