1. results;Nogradi;Chem Commun Tetrahedron,1970
2. von;Doering;Tetrahedron,1960
3. For example see;Olah;Am Chem SOC Am Chem SOC Am Chem SOC Am Chem SOC,1990
4. for their valuable contribution REFERENCES;KOMATSU;Chem Lett
5. For example see;Battiste;Am Chem SOC