1. Heterocycles by cycloaddition. Part 13. Part 12: Kobayashi, T.; Minemura, H.; Kato, H. Heterocycles, 1995, 40, 311–317.
2. Partly reported in a preliminary form: Kato, H.; Kobayashi, T.; Ciobanu, M.; Iga, H.; Akutsu, A.; Kakehi, A. Chem. Commun., 1996, 1011–1012.
3. Review on cycloaddition reactions of mesoionic compounds: Potts, K.T. Mesoionic Ring Systems. In 1,3-Dipolar Cycloaddition Chemistry, Padwa, A. Ed.; Wiley, New York, Vol. 2, 1984, pp. 1–82.
4. Reviews on mesoionic compounds including cycloaddition: Ohta, M.; Kato, H. Sydnones and Other Mesoionic Compounds. In Nonbenzenoid Aromatics, Snyder, J.P. Ed; Academic, New York, 1969, pp. 117–248; Ramsden, C.A. Meso-ionic Heterocycles. In Comprehensive Organic Chemistry, Barton, D.H.R.; Ollis, W.D. Eds; Pergamon, Oxford, Vol. 4, 1979, pp. 1171–1228; Ollis, W.D.; Ramsden, C.A. Meso-ionic Heterocycles. In Adv. Heterocycl. Chem., Katritzky, A.R.; Boulton, A.J. Eds.; Academic, New York, Vol. 19, 1976, pp. 1–122; Newton, C.G.; Ramsden, C.A. Tetrahedron, 1982, 38, 2965–3011; Ollis, W.D.; Stanforth, S.P. Tetrahedron, 1985, 41, 2239–2329; Gingrich, H.L., Baum, J.S. Mesoionic Oxazoles. In The Chemistry of Heterocyclic Compounds, Turchi, I.D. Ed. Wiley, New York, Vol. 45, 1986, pp. 731–961.
5. Matsukubo, H.; Kato, H. J. Chem. Soc., Chem. Commun., 1974, 412–413; Nakazawa, S.; Hirakawa, K.; Kiyosawa, T.; Kato, H. J. Chem. Soc., Chem. Commun., 1974, 621; Matsukubo, H.; Kato, H. J. Chem. Soc., Perkin Trans. 1, 1975, 632–635; Matsukubo, H.; Kojima, M.; Kato, H. Chemistry Lett., 1975, 1153–1154; Kato, H.; Nakazawa, S.; Kiyosawa, T.; Hirakawa, K. J. Chem. Soc., Perkin Trans. 1, 1976, 672–675; Kobayashi, T.; Minemura, H.; Kato, H. Heterocycles, 1995, 40, 311–317. Cf. Also: Eicher, T.; Schaefer, V. Tetrahedron, 1974, 30, 4025–4029; Potts, K.T.; Baum, J.; Houghton, E. J. Org. Chem., 1976, 41, 818–824.